EE OBJECTIVES-TERMS LOOKSFAM.docx

**EE OBJECTIVES/TERMS LOOKSFAM** **RESISTANCE/OHM'S LAW** 1. An electron has negative charge of \_\_\_\_\_\_\_coulomb. A. 9.8 x 10\^-22 B. 9.8 x 10\^-19 C. 1.6 x 10\^-22 D. 1.6 x 10\^-19 2. Electric current in a wire is the flow of \_\_\_\_\_\_. A. Bound electrons B. Atoms C. Free...

**EE OBJECTIVES/TERMS LOOKSFAM** **RESISTANCE/OHM'S LAW** 1. An electron has negative charge of \_\_\_\_\_\_\_coulomb. A. 9.8 x 10\^-22 B. 9.8 x 10\^-19 C. 1.6 x 10\^-22 D. 1.6 x 10\^-19 2. Electric current in a wire is the flow of \_\_\_\_\_\_. A. Bound electrons B. Atoms C. Free electrons D. Valence 3. Prevents electric current to flow and at the same time electrical energy is converted into heat energy. A. Capacitance B. Inductance C. Impedance D. Resistance 4. Conductors have \_\_\_\_\_\_temperature coefficient of resistance. A. Negative B. Positive C. Zero D. None of these 5. The maximum number of electrons that can be accommodated in the last orbit of an atom is \_\_\_\_\_\_\_\_\_. A. 4 B. 8 C. 2 D. 6 6. The electrons in the last orbit of an atom are called \_\_\_\_electrons. A. Free B. Bound C. Valence D. Thermionic 7. If the number of valence electrons of an atom is less than 4, the substance is usually \_\_\_\_\_\_\_. A. An insulator B. A semi-conductor C. A conductor D. None of these 8. If the number of valence electrons of an atom is more than 4, the substance is usually \_\_\_\_\_\_\_. A. An insulator B. A conductor C. A semi-conductor D. None of these 9. If the number of valence electrons of an atom is exactly 4, then the substance is usually \_\_\_\_\_\_. A. An insulator B. A semi-conductor C. A metal D. A conductor 10. Insulators and semi-conductors have \_\_\_\_\_\_temperature coefficient resistance. A. Positive B. Zero C. Negative D. None of these 11. The temperature coefficient of resistance of a conductor \_\_\_\_\_\_\_with the rise in temperature. A. Remains the same B. Increases C. Approaches zero D. Decreases 12. The value of the temperature coefficient of resistance of a conductor depends upon \_\_\_\_\_\_\_. A. Length of the material B. Volume of the material C. Cross-sectional area of the material D. Nature of the material and temperature 13. An alloy of 40% nickel and 60% copper used for making rheostat and wire-wound resistors is called \_\_\_\_\_\_\_. A. Eureka B. Alnico C. Nichrome D. None of these 14. Out of the following, select the best conductor of electricity. A. Graphite B. Porcelain C. China clay D. None of these 15. Which of the following statements is correct? A. Resistance does not play an important role in electrical engineering. B. The resistance of a wire does not depend upon its material. C. The resistance of most of the materials is independent of the temperature. D. The resistance of the conductor is the hindrance by which the conductor opposes the flow of the current. 16. Resistance of a conductor increases when \_\_\_\_\_\_\_. A. Its length increases B. Its area increases C. Both area and length increases D. Specific resistance is kept constant 17. The specific resistance depends upon \_\_\_\_\_\_\_. A. The area and length of the conductor B. The material of the conductor and its area C. The nature of the material of the conductor D. The area of the conductor 18. The resistance of a conductor, when its temperature is increased \_\_\_\_\_\_. A. Remains constant B. Varies C. Increases D. Decreases 19. When current flows through a conductor, heat is produced because \_\_\_\_\_\_. A. Heat is directly proportional to the square B. Of electronic collision C. Of interatomic collision D. Of Joules law 20. Heating effect of electric current has undesirable side effect in \_\_\_\_\_\_\_-. A. Electric oven B. Immersion heater C. Electric iron D. Vacuum cleaner 21. The resistance of carbon when its temperature is decreased \_\_\_\_\_\_. A. Increases B. Remains the same C. Decreases D. Increases enormously 22. The curve representing Ohm's Law is \_\_\_\_\_. A. A parabola B. Sine function C. Linear D. A hyperbola 23. The condition in Ohm's Law is that \_\_\_\_\_\_\_. A. Ratio V/I should be constant B. Current should be proportional to voltage C. Temperature should vary D. Temperature should remain constant 24. Ohm's Law does not apply to \_\_\_\_\_\_\_. A. Conductors B. Semi-conductors C. AC circuit D. All of these 25. Ohm's Law is applicable to \_\_\_\_\_\_\_\_. A. Electric arc B. Gas discharge lamps C. Rectifying devices D. None of these 26. Ohm's can be applied with certain reservations to \_\_\_\_\_\_\_. A. Rectifying devices B. Electrolytes C. Semi-conductors D. Thermionic valves 27. The presence of an electric current is made known by \_\_\_\_\_\_. A. Flashing B. Cracking C. Effects produced D. Electric shock 28. Voltage applied across a circuit, acts as \_\_\_\_\_\_\_. A. Mass of electrons B. Negative ions C. A force D. None of these 29. In a series circuit, the current is \_\_\_\_\_\_. A. Constant B. Proportional to the resistance C. Different in different resistors D. Always zero 30. Resistors commonly used in power circuits are \_\_\_\_\_\_\_. A. Carbon resistors B. Etched circuit resistors C. Wire wound resistors D. None of these 31. Electrical appliances are not connected in series because \_\_\_\_\_. A. Series circuit is complicated B. Appliances have different current ratings C. Power loss is more D. None of these 32. Electrical appliances are connected in parallel because \_\_\_\_\_\_\_. A. It is a simple circuit B. It results in reduced power loss C. It makes the operation of the appliances independent of each other D. Less current is required 33. Cells are connected in parallel when \_\_\_\_\_is required. A. High voltage B. High current C. High power D. None of these 34. Cells are connected in parallel when \_\_\_\_\_ is required. A. Low voltage B. High voltage C. High power D. High current 35. A material used in making heating elements. A. Carbon B. Eureka C. Tungsten D. Nichrome **[ELECTROSTATICS/CAPACITANCE]** 1. The relation between absolute permittivity (ε0) of air, absolute permeability (µ0) of air and velocity of light (C)is given by \_\_\_\_\_\_. A. C\^2 = µ0ε0 B. C\^2 = µ0/ε0 C. C\^2 = ε0/µ0 D. C\^2 = 1/µ0ε0 2. Electric lines of force leave or enter the charged surface at an angle of \_\_\_\_\_\_\_. A. 30˚ B. 90˚ C. 60˚ D. 45˚ 3. Electric field intensity is expressed in \_\_\_\_\_\_. A. Volt/meter B. Newton/coulomb C. Newton/meter D. Either a or b 4. Electric field intensity is a \_\_\_\_\_\_.BP Sept. 2012 A. Scalar quantity B. Vector quantity C. Phasor D. None of these 5. Electric field intensity at a point due to a given charge \_\_\_\_\_\_if the relative permittivity of the medium decreases. A. Decreases B. Remains the same C. Increases D. None of these 6. Electric flux density is a \_\_\_\_\_\_. A. Vector quantity B. Scalar quantity C. Phasor D. None of these 7. The absolute permittivity of a material is \_\_\_\_\_\_. A. Electric field intensity x electric field density B. (Electric field density)\^2/Electric field intensity C. Electric field intensity/Electric field density D. Electric field density/Electric field intensity 8. Electric field intensity at a point is numerically equal to the \_\_\_\_\_\_ at that point. A. Potential gradient B. Potential C. Dielectric constant D. None of these 9. Electric potential is a \_\_\_\_\_\_\_. A. Vector quantity B. Scalar quantity C. Phasor D. None of these 10. A body is \_\_\_\_\_\_\_\_under ordinary conditions. A. Positively charged B. Negatively charged C. Neutral D. None of these 11. A positively charged body has \_\_\_\_\_\_. A. Excess of electrons B. Deficit of electrons C. Excess of electrons D. Deficit of neutrons 12. A negatively charged body has \_\_\_\_\_\_\_\_. A. Deficit of electrons B. Deficit of neutrons C. Excess of neutrons D. Excess of electrons 13. This paper does not exhibit electricity because it contains the same number of \_\_\_\_\_\_\_. A. Protons and electrons B. Neutrons and electrons C. Neutrons and positrons D. None of these 14. The value of the absolute permittivity of air is \_\_\_\_\_\_. A. 9 x 10\^9 F/m B. 5 x 10\^6 F/m C. 8.854 x 10\^-12 F/m D. 9 x 10\^-9 F/m 15. The relative permittivity of a material is 10. Its absolute permittivity will be \_\_\_\_\_\_\_\_\_\_\_\_. A. 9 x 10\^8 F/m B. 5 x 10\^-5 F/m C. 9 x 10\^-10 F/m D. 8.854 x 10\^-11 F/m 16. The force between two charges placed at a given distance apart \_\_\_\_\_\_as the relative permittivity of the medium is increased. A. Decreases B. Increases C. Remains the same D. None of these 17. Another name for relative permittivity is \_\_\_\_\_\_\_. A. Dielectric constant B. Electric intensity C. Dielectric strength D. Potential gradient 18. Another name for dielectric strength is \_\_\_\_\_\_. A. Potential gradient B. Dielectric constant C. Breakdown voltage D. Electric intensity 19. Which of the following materials has the highest dielectric strength? A. Oiled paper B. Mica C. Air D. Glass 20. In electric iron \_\_\_\_\_\_ is used as the insulating material. A. Mica B. Oiled paper C. Paraffin D. None of these 21. What will happen to an insulating medium if voltage more than the breakdown voltage is applied to it? BP Sept 2006 A. It will melt B. It will get punctured C. It will become magnetic D. Its molecular form will change 22. Capacitors are used to \_\_\_\_\_\_\_\_. A. Pass AC and DC B. Block AC and pass DC C. Block DC and pass AC D. Block AC and DC 23. The effect of the dielectric in a capacitor is to \_\_\_\_\_\_. A. Increase the capacitance B. Decrease the capacitance C. Increase the distance between plates D. Reduce the working voltage 24. In a radio, a gang capacitor is a type of \_\_\_\_\_. A. Air capacitor B. Ceramic capacitor C. Paper capacitor D. Electrolytic capacitor 25. The power dissipated in a pure capacitor is \_\_\_\_\_\_. A. Maximum B. Minimum C. Depends on the size D. Zero 26. In a capacitor, the electric charge is stored in the \_\_\_\_\_. A. Metal plates B. Dielectric C. Dielectric and metal plates D. None of these 27. One farad is \_\_\_\_\_\_. A. Coulomb-joule B. Joule/volt C. One coulomb/volt D. One volt/coulomb 28. If a dielectric is placed in an electric field, the field strength \_\_\_\_\_. A. Becomes zero B. Remains the same C. Increases D. Decreases 29. A circuit component which opposes the change in circuit voltage is \_\_\_\_\_\_\_. A. Resistance B. Inductance C. Capacitance D. None of these 30. Internal heating of a capacitor is attributed to its \_\_\_\_\_\_. A. Electron movement B. Leakage resistance C. Plate vibration D. Dielectric charge 31. The ohmmeter reading for a shorted capacitor is \_\_\_\_\_\_. A. Infinity B. Zero C. Few mega ohms D. Few kilo ohms 32. A trimmer is a variable capacitor in which capacitance is obtained by changing the \_\_\_\_\_\_\_\_. A. Plate area B. Dielectric C. Distance between plates D. Both a and b 33. A gang capacitor is a variable capacitor in which capacitance is varied by changing \_\_\_\_\_\_. A. Plate area B. Distance between plates C. Dielectric D. None of these 34. When the movable plates of a gang capacitor completely overlap the fixed plates, the capacitance of the capacitor is \_\_\_\_\_\_. A. Minimum B. One half of maximum C. Maximum D. None of these 35. The charging of a capacitor through a resistance follows \_\_\_\_\_. A. Linear law B. Exponential law C. Square law D. None of these 36. The energy stored in a capacitor is given by \_\_\_\_\_\_. A. C V\^2/2 B. Q\^2/2 C C. C V D. Either a or b 1. Cores of magnetic equipments have \_\_\_\_\_\_. A. Low permeability B. High permeability C. Least permeability D. None of these 2. As the magnetic field intensity increases, the relative permeability of a material \_\_\_\_\_. A. Increases B. Remains the same C. Decreases D. Becomes zero 3. When the relative permeability of a material is slightly less than 1, then the material is called \_\_\_\_\_\_. A. Diamagnetic B. Ferromagnetic C. Paramagnetic D. None of these 4. When the relative permeability of a material is slightly greater than 1, then the material is called \_\_\_\_\_\_\_. A. Diamagnetic B. Ferromagnetic C. Paramagnetic D. None of these 5. When the relative permeability of a material is much greater than 1, then the material is \_\_\_\_\_\_\_\_. A. Diamagnetic B. Ferromagnetic C. Paramagnetic D. None of these 6. Out of the following \_\_\_\_\_\_is the diamagnetic material. A. Silver B. Aluminum C. Air D. Iron 7. Out of the following, \_\_\_\_\_\_is the paramagnetic material. A. Carbon B. Oxygen C. Copper D. Bismuth 8. A current carrying conductor is placed in a uniform magnetic field. The maximum force will act on the conductor when the conductor is at an angle of \_\_\_\_\_\_to the magnetic field. A. 0˚ B. 60˚ C. 90˚ D. 45˚ 9. The magnetism that remains in a magnetic material after the magnetizing force has been removed is called \_\_\_\_\_\_. A. Permeability B. Residual C. Induction D. Saturation 10. Permeance is analogous to \_\_\_\_\_\_\_\_. A. Reluctance B. Resistance C. Conductance D. None of these 11. Magnetic fields do not interact with \_\_\_\_\_\_\_. A. Stationary electric charges B. Moving electric charges C. Stationary permanent magnets D. Moving permanent magnets 12. A current is flowing east along a power line. If we neglect the earth's field, the direction of the magnetic field below the line is \_\_\_\_\_\_\_. A. South B. North C. West D. East 13. When a magnetized iron bar is strongly heated, its magnetic field \_\_\_\_\_\_. A. Becomes stronger B. Reverses its direction C. Becomes weaker D. Remains the same 14. Permanent magnets are made up of \_\_\_\_\_\_\_. A. Iron B. Nickel C. Soft steel D. Hardened steel 15. Temporary magnets are made up of \_\_\_\_\_\_\_. A. Hardened steel B. Soft steel C. Soft iron D. Tungsten steel 16. One would find a permanent magnet in \_\_\_\_\_\_\_\_. A. Relays B. Earphones C. Dynamic loudspeakers D. None of these 17. One use of a temporary magnet in \_\_\_\_\_\_. A. Motors B. Electric bells C. Electric buzzers D. All of these 18. The force acting between two magnetic poles is \_\_\_\_\_\_distance between them. A. Inversely proportional to the square of the B. Directly proportional to the square of the C. Inversely proportional to the D. Directly proportional to the 19. The force between two magnetic poles is \_\_\_\_\_the relative permeability of the medium. A. Directly proportional to B. Inversely proportional to C. Independent of D. None of these 20. The absolute permeability of vacuum or space is \_\_\_\_\_H/m. A. 4ח x 10\^-12 B. 4ח x 10\^-7 C. 4ח x 10\^-10 D. 4ח x 10\^-8 21. A bunch of magnetic lines of force is called \_\_\_\_\_\_\_. A. Magnetic flux density B. Magnetic flux intensity C. Magnetic flux D. None of these 22. One weber of magnetic flux is equal to \_\_\_\_\_magnetic lines of force. A. 10\^5 B. 10\^6 C. 10\^7 D. 10\^8 23. Magnetic flux density is a \_\_\_\_\_\_\_. A. Scalar quantity B. Vector quantity C. Phasor D. None of these 24. Which of the following does not belong to the group? A. Tesla B. Gauss C. Lines/sq cm D. Flux density 25. The saturation flux density for most magnetic materials is about \_\_\_\_\_Wb/m\^2. A. 0.5 B. 5 C. 2 D. 1 26. Magnetic field intensity is a \_\_\_\_\_\_. A. Vector quantity B. Scalar quantity C. Phasor D. None of these 27. Unit of magnetic field intensity is \_\_\_\_\_\_\_. A. Ampere-turns/meter B. Ampere-turns/weber C. Newtons/Weber D. Either a or c 28. A current carrying loop in a magnetic field always tends to rotate until the plane on the loop is \_\_\_\_\_\_\_. A. Parallel to the field B. At 45˚ angle with field C. Perpendicular to the field D. Either parallel or perpendicular to the field depending on the current direction 29. The nature of the force responsible for an electric motor is \_\_\_\_\_. A. Electrical B. Magnetic C. A combination of electrical and magnetic D. Either electrical or mechanical, depending on the motor design 30. Two parallel wires carry currents in the same direction. A. The wires repel each other B. Torques act on the wires C. Neither torques nor forces act on the wires D. The wires attract each other. 31. A coil of wire in the form of a helix is called \_\_\_\_\_. A. Solenoid B. Reactor C. Toroid D. Ballast 32. The opposition offered by a material to the production of magnetic field in it is called \_\_\_\_\_\_. A. Permeance B. Hindrance C. Reluctance D. None of these 1. In any dc generator, the emf generated in the armature is maximum when \_\_\_\_\_\_. A. Rate of change of flux linked is minimum B. Rate of change of flux linked is maximum C. Flux linked with conductor is maximum D. Flux linked with conductors is minimum 2. A simple method of increasing the voltage of a dc generator is to \_\_\_\_\_\_. A. Increase the air gap density B. Increase the speed of rotation C. Decrease the speed of rotation D. Increase the length of the armature 3. The method which can be used to improve commutation process is \_\_\_\_\_\_\_\_. A. Increasing the resistance of the brushes B. Reducing the number of turns in the armature coil and hence the number of commutator segments C. To neutralize the reactance voltage by producing a reversing emf in the short circuited coil under commutation. D. All of these 4. The function of interpole is to \_\_\_\_\_\_. A. Neutralize the reactance voltage and help in commutation process B. Neutralize the cross-magnetizing effect of armature reaction C. Neutralize the demagnetizing effect of armature reaction D. A and B 5. Interpole winding is connected in \_\_\_\_\_\_\_ with the armature and compensating winding is connected in \_\_\_\_\_\_\_with the armature. A. Series, series B. Shunt, series C. Series, shunt D. Shunt, shunt 6. The function of an equalizer ring is \_\_\_\_\_\_\_. A. To avoid unequal distribution of current at the brushes B. To help to get sparkles commutation C. Both a and b D. None of these 7. Which of the following is most suitable for running in parallel operation? A. Shunt generator B. Series generator C. Compound generator D. All of these 8. Critical resistance of a dc generator, Rc is \_\_\_\_\_\_. A. Rc α (speed)\^2 B. Rc α (speed) C. Rc α (speed)\^3 D. Rc α (speed)\^-1 9. External characteristics of a dc generator can be obtained by \_\_\_\_\_. A. Internal characteristics B. No-load saturation characteristics C. Armature resistance drop D. Both a and b 10. Shunt generators are used where the main requirement is a constant \_\_\_\_\_\_\_\_. A. Current and voltage B. Current C. Voltage over a wide load range D. Voltage over a narrow load range 11. Equalizer connections are required when paralleling two \_\_\_\_\_. A. Compound generators B. Series generators C. Shunt generators D. All of these 12. Interpole winding is normally connected in \_\_\_\_\_\_. A. Parallel with field winding B. Series with the field winding C. Parallel with the load D. Series with the load 13. In dc generators lap winding is used for \_\_\_\_\_\_\_.(APRIL 2024 EE) A. Low voltage, low current B. High voltage, high current C. Low voltage, high current D. High voltage, low current 14. A dc generator preferred for charging batteries is \_\_\_\_\_\_. A. Shunt B. Series C. Long shunt compound D. Short shunt compound 15. Which of the following components of a dc generator plays vital role for providing direct current of a dc generator? A. Dummy coils B. Eye bolt C. Equalizer rings D. Commutator 16. In a dc generator the ripples in the direct emf and generated are reduced by \_\_\_\_\_\_\_. A. Equalizer rings B. Using commutator with large number of bars C. Using carbon brushes of superior quality D. None of these 17. Which loss in dc generator varies with load? A. Copper loss B. Hysteresis loss C. Eddy current loss D. Windage loss 18. In dc generator, the cause of rapid brush wear may be \_\_\_\_\_. A. Imperfect contact B. Sever sparking C. Rough commutator surface D. Any of these 19. In a shunt generator, the voltage build up is generally restricted by \_\_\_\_\_\_. A. Speed limitation B. Armature heating C. Saturation of core D. A and B 20. The armature of a dc generator is laminated to \_\_\_\_\_\_. A. Reduce the bulk B. Insulate the core C. Reduce eddy current loss D. Provide passage for cooling air 21. How would you determine, from visual observation of the armature winding, whether a generator is lap or wave wound? BP Sept. 2012. A. Connection to the field winding B. Connection to commutator C. Connection to brushes D. The direction of the end connection 22. What classification is given to a generator that receives its field excitation current from internal source? A. Self-excited B. Controlled excitation C. Separately-excited D. Internally excited 23. The shunt field of a compound generator is connected across both the series field and the armature. This connection is known as: A. Short shunt B. Long shunt C. Differential compound D. Cumulative compound 24. Residual magnetism is necessary in a \_\_\_\_\_generator. A. Separately excited B. Self-excited C. Both of these D. None of these 25. Electric dc generators have normally, an over-all efficiency of the order of \_\_\_\_\_\_%. A. 60 to 80 B. 75 to 85 C. 80 to 90 D. 85 to 95 26. The armature magnetic field has effect that \_\_\_\_\_\_\_. A. It demagnetizes or weakens the main flux B. It cross magnetizes or distorts the main flux C. It magnetizes or strengthens the main flux D. Both a and b 27. Brushes are always placed \_\_\_\_\_\_\_\_. A. Along magnetic neutral axis. B. Along geometric neutral axis. C. Perpendicular to magnetic neutral axis. D. Perpendicular to geometric neutral axis. 28. Magnetic neutral axis makes an electrical angle of \_\_\_\_\_\_degrees with the flux passing through the armature. A. 0 B. 90 C. 45 D. 180 29. In a dc generator the flux is seen to be \_\_\_\_\_\_at the trailing pole tips and also \_\_\_\_\_\_at the leading pole tips. A. Weakened, weakened B. Weakened, crowded C. Crowded, weakened D. Same, same 30. The function of the compensating winding is to neutralize \_\_\_\_\_\_. A. Reactance voltage generated due to commutation. B. Cross-magnetizing effect of armature reaction C. Demagnetizing effect of armature reaction D. All of these 31. In the commutation process it is the \_\_\_\_\_\_\_\_. A. Current which is getting reversed B. Voltage which is getting reversed C. Both a and b D. None of these 32. Which of the following helps in reducing the effect of armature reaction in dc generator? A. Compensating winding B. Interpole winding C. Shading coils D. A and B 33. In most generators the output voltage is induced by \_\_\_\_\_\_. A. Rotating magnetic field past stationary coils B. Relative motion between the field and the armature coils C. Converting electrical energy to mechanical energy D. None of these 1. Which of the following is a correct statement about a series motor? A. The field winding consists of thicker wire and less turns. B. It can run easily without load C. It has an almost constant speed D. It has a poor torque 2. Which of the following dc motors has the least drop in speed between no-load and nominal load? A. Shunt motor with commutating poles B. Series motor without commutating poles C. Compound motor without commutating poles D. Series motor with commutating poles 3. The speed of a series motor at no-load is \_\_\_\_\_\_\_\_. A. Zero B. 3,600 rpm C. 3,000 rpm D. Infinity 4. The speed of a dc series motor decreases if the flux in the field winding \_\_\_\_\_\_. A. Remains constant B. Increases C. Decreases D. None of these 5. Which of the following motors is used to drive the constant speed line shafting lathes, blowers and fans? A. Shunt B. Series C. Cumulative compound D. Differential compound 6. If the back emf in a dc motor is absent then \_\_\_\_\_\_\_. A. Motor will not run at very high speed B. Motor will run at very low speed C. Motor will not run at all D. Motor will burn 7. The field flux of a dc motor can be controlled to achieve \_\_\_\_\_\_\_. A. Speeds lower than rated speed B. Speed higher than rated speed C. Speed at rated load D. None of these 8. By providing a variable resistance across the series field (diverter) in a dc series motor, speeds above normal can be obtained because \_\_\_\_\_\_\_\_. A. Armature current decreases B. Flux is reduced C. Line current decreases D. None of these 9. DC series motors are best suited for traction work because \_\_\_\_\_\_\_. A. Torque is proportional to the square of the armature current and speed is inversely proportional to the torque. B. Torque is proportional to the square of the armature current and speed is proportional to the torque. C. Torque and speed are proportional to the square of the armature current D. None of these 10. A dc series motor is started without load. The effect is that \_\_\_\_\_\_. A. The torque increases rapidly B. The speed increases rapidly C. The current drawn increases rapidly D. The back emf decreases 11. The direction of rotation of a dc series motor can be reversed by interchanging the\_\_\_\_\_. A. Supply terminals only B. Field terminals only C. Supply as well as field terminals D. None of these 12. The motor used for intermittent, high torque is \_\_\_\_\_\_. A. Shunt motor B. Series motor C. Differential compound motor D. Cumulative compound motor 13. If the field of a dc shunt motor is opened, then \_\_\_\_\_\_. A. It will continue to run at its rated speed B. The speed of the motor will become very high C. The motor will stop D. The speed of the motor will decrease 14. Which of the following dc motors is used for rolling mills? A. Shunt motor B. Cumulative compound motor C. Differential compound motor D. Series motor 15. Armature reaction is attributed to the \_\_\_\_\_\_. A. Effect of magnetic field set -- up by the armature current B. Effect of the magnetic field set -- up by the field current C. Copper loss in the armature D. Effect of magnetic field set -- up by the back emf 16. What will happen if the supply terminals of dc shunt motor are interchanged? A. Motor will stop B. Motor will run at its normal speed in the same direction as it was running. C. The direction of rotation will be reversed D. Motor will run at lower speed than the normal speed in the same direction 17. The rotating part of a dc motor is known as \_\_\_\_\_\_\_\_\_. A. Pole B. Armature C. Stator D. Carbon brush 18. Carbon brushes are used on dc motors to \_\_\_\_\_\_\_\_. A. Brush off carbon deposits B. Provide a path for flow of current C. Prevent overheating of armature winding D. Prevent sparking during commutation 19. Voltage equation for dc motor is \_\_\_\_\_\_\_\_\_. A. V = Eb + IaRa B. Eb = V + IaRa C. V = Eb -- IaRa D. Eb = V --IfRf 20. Condition for maximum power output for a dc motor is \_\_\_\_\_. A. Eb = V B. Eb = IaRa + IfRf C. Eb = V/2 D. Eb = IaRa/2 21. The speed of a dc motor is \_\_\_\_\_\_. A. Directly proportional to back emf and inversely proportional to flux. B. Inversely proportional to back emf and directly proportional to flux. C. Directly proportional to emf as well as flux D. Inversely proportional to emf as well as flux. 22. The highest speed attained by a dc shunt motor is \_\_\_\_\_\_. A. Equal to infinity at rated flux B. Higher than no-load speed at rated flux C. Equal to no-load speed at rated flux D. Lower than no-load speed at rated flux 23. In a dc motor iron losses occurs in the \_\_\_\_\_\_. A. Yoke B. Field C. Armature D. None of these 24. The dummy coil in the dc machines is used to \_\_\_\_\_\_. A. Eliminate reactance voltage B. Eliminate armature reaction C. Bring about mechanical balance of armature D. Eliminate harmonics developed in the machine 25. An external resistance is added in series with the field of a dc shunt motor. When the motor runs, the effect of resistance is \_\_\_\_\_\_\_\> A. To reduce the speed of the motor B. To increase the speed of the motor C. To reduce the armature current of the motor D. To reduce the losses 26. The speed of a dc shunt motor is required to be more than full load speed. This is possible by \_\_\_\_\_\_\_. A. Increasing the armature current B. Decreasing the armature current C. Increasing the excitation current D. Reducing the field current 27. If speed of a dc shunt motor increases, the back emf \_\_\_\_\_\_\_\_\_. A. Increases B. Decreases C. Remains constant D. Decreases and then increases 28. As the load is increased, the speed of a dc shunt motor will \_\_\_\_\_\_\_. A. Remains constant B. Increase slightly C. Increase proportionately D. Reduce slightly 29. The current drawn by the armature of a dc shunt motor is \_\_\_\_\_\_\_\_. A. V/Ra B. (V - Eb)/Ra C. Eb/Ra D. (Eb -- V)/Ra 30. If the current in the armature of a dc series motor is reduced to 50%, the torque of the motor will become \_\_\_\_\_\_\_. A. 50% of the previous value B. 25% of the previous value C. 150% of the previous value D. 75% of the previous value 31. The shunt field current flowing in a short shunt compound dc motor is given by \_\_\_\_\_\_\_. A. Ish = V/Rsh B. Ish = (V+IscRsc)/Rsh C. Ish = V -- (IscRsc)/Rsh D. None of these 32. In dc shunt motor, if the terminal voltage is reduced to half and torque remains the same, then \_\_\_\_\_\_\_\_. A. Speed will be half and armature current also will be half B. Speed will be half but armature current remains the same C. Speed will be half and armature current becomes double D. Speed and armature will be the same 33. One dc motor drives another dc motor. The second dc motor when excited and driven \_\_\_\_\_\_. A. Runs as a generator B. Also runs as a motor C. Heats excessively D. None of these 34. A 4 pole, simplex lap wound armature has 400 conductors and flux per pole of 25 mWb. The emf generated when running at 600 rpm, will be \_\_\_\_\_\_V. A. 240 B. 100 C. 60 D. 30 35. The torque of a motor is \_\_\_\_\_\_\_\_. A. The force acting on the motor B. The tangential force on the rotor multiplied by the rotor radius. C. The electrical power of the motor D. None of these 36. The output power of any electrical motor is taken from the \_\_\_\_\_. A. Armature B. Coupling mounted on the shaft C. Conductors D. Poles 37. The power stated on the nameplate of any motor is always the \_\_\_\_\_\_\_\_. A. Output power at the shaft B. Power drawn in KVA C. Power drawn in KW D. Gross power 38. A starter is necessary to start a dc motor because it \_\_\_\_\_\_\_. A. Starts at the motor B. Limits the motor speed C. Limits the emf to a sale value D. Limits the starting current to a safe value 39. The direction of rotation of a dc motor is reversed by \_\_\_\_\_\_. A. Reversing armature connection B. Interchanging the armature and field connection C. Adding resistance to the field circuit D. Reversing supply connection 40. When the electric train is moving down a hill, the dc motor acts as dc \_\_\_\_\_\_\_\_. A. Series motor B. Shunt motor C. Series generator D. Shunt generator 41. Which of the following dc motors is suitable for high starting torque? A. Cumulative compound B. Differential compound C. Series D. Shunt 42. Which of the following dc motors is used for flywheel drive? A. Shunt B. Series C. Compound D. Universal 43. Why is the air gap between the stator and armature of an electric motor kept as small as possible? A. To get a stronger magnetic field B. To make the rotation easier C. To reach a higher speed of rotation D. To improve the air circulation 44. Interpoles are meant for \_\_\_\_\_\_\_\_. A. Increasing the speed of the motor B. Decreasing counter emf C. Reducing sparking at the commutator D. Converting armature current to dc 45. It is preferable to start a dc series motor, with some mechanical load on it because \_\_\_\_\_\_\_. A. It will not run at no-load B. It acts as starter of the motor C. It may develop excessive speed and change itself D. None of these 46. If the flux of a dc motor approaches zero, its speed will approach \_\_\_\_\_\_\_. A. Infinity B. Zero C. A stable value nearer to the rated speed D. None of these 47. A 230V dc series motor is connected to a 230V ac supply. It will \_\_\_\_\_. A. Run slowly B. Not run at all C. Run with less efficiency D. Burn 48. Which of the following statements is incorrect.If a starter is not used with large dc motor, it will draw a starting current which \_\_\_\_\_\_. A. Is many times the full load current B. Will produce excessive line voltage drop C. Will damage the commutator D. Will produce very low starting torque **[AC CIRCUITS]** 1. A. Three B. One C. Two D. Four 2. A. Two B. Three C. Four D. One 3. A. Load on one of the phases is zero B. Power factor is unity C. Power factor is 0.5 D. Neutral is grounded 4. A. Balanced and unbalanced load B. Unbalanced load only C. Balanced load only D. Unity power load only 5. A. Power factor is unity B. Power factor is 0.5 C. Load on one of the phases is zero D. A neutral wire is provided 6. A. And so are the line currents B. To the phase voltages C. But the line currents are unequal D. But the phase voltages are unequal 7. A. Open delta system B. Three phase delta system C. Three phase wye system with neutral wire D. Three phase wye system without neutral 8. A. 90 degrees B. 120 degrees C. 180 degrees D. 360 degrees divided by the number of phases 9. A. The phasor difference of the two phase voltages B. The phasor sum of the two phase voltages C. 0.707 times the phase voltage D. 1.414 times the phase voltage 10. A. 0.707 times the phase current B. 1.732 times the phase current C. Equal to the phase current D. 1.414 times the phase current 11. A. Step down current B. Extra step up voltage C. Extra step up current D. Extra step up power 12. A. 1.414 times the phase current B. Phasor sum of the two phase currents C. Equal to the phase current D. 1.732 times the phase current 13. A. Equal to that of delta system B. 1.414 times the delta system C. 1.732 times the delta system D. Three times the delta system 14. A. 3 wire, open delta connection B. 4 wire, wye connection C. 3 wire, delta connection D. 3 wire, wye connection 15. A. Two B. One C. Four D. Three 16. A. Power factor is unity B. Power factor is 0.707 C. Power factor is 0.866 D. A neutral wire is provided 17. A. The power factor of each phase will be the same B. The power factor of each phase may be different C. The power factor of at least one phase must leading D. The power factor of at least one phase must be lagging 1. High voltage alternators are usually of the rotating field type. This means the generated voltage is applied \_\_\_\_\_\_\_. A. Directly to load B. Directly to rotor C. Through slip rings to load D. None of these 2. One of the advantages of a short pitched winding is the \_\_\_\_\_\_\_\_\_. A. Reduction of voltage B. Reduction of circulating current C. Increase of induction D. Elimination of harmonics 3. Pitch factor is the ratio of the emf's of \_\_\_\_\_\_\_. A. Distributed winding to full pitch winding B. Short-pitch coil to full pitch coil C. Full pitch winding to short pitch winding D. Full pitch winding to concentrated winding 4. The imaginary or fictitious part of a synchronous reactance takes care of \_\_\_\_\_\_. A. Voltage regulation B. Inductive reactance C. Armature reaction D. Copper losses 5. Synchronous reactance consists of two components, namely \_\_\_\_\_\_. A. Leakage reactance and fictitious reactance B. Leakage reactance and capacitive reactance C. Armature resistance and leakage reactance D. None of these 6. Majority of 3 phase alternators in use have \_\_\_\_\_\_\_\_. A. Rotating armature winding B. Stationary field winding C. Rotating field winding D. None of these 7. Alternators mostly work on rotating field type principle which is different from dc machines where the field is stationary. Therefore the alternators \_\_\_\_\_\_\_\_. A. Don't obey Faradays law B. Work on Faradays law C. Do not obey Lenz law D. Don't obey Ohm's law 8. High speed alternators have a rotor construction of \_\_\_\_\_\_\_. A. Salient pole type B. Dc armature type C. Squirrel cage type D. Non-salient pole type 9. Alternators are designed to generate \_\_\_\_\_\_\_. A. Variable frequencies B. Definite currents C. Definite frequencies D. Definite power factor 10. The diameter of high speed turbo generators as compared to hydroelectric ones are \_\_\_\_\_\_\_\_\_. A. Smaller because speed is high B. Smaller because speed is loss C. Larger because speed is high D. None of these 11. The slip rings employed in a 3 phase alternator in hydrostation are insulated for \_\_\_\_\_\_\_. A. Extra high voltage B. Low voltage C. Full armature voltage D. Very high voltage 12. When the speed of the alternator increases, the frequency \_\_\_\_\_\_. A. Decreases B. Remains the same C. Increases D. None of these 13. When load power factor is unity, the armature flux of an alternator is \_\_\_\_\_\_\_. A. Demagnetizing B. Square wave form C. Aiding the field flux D. Cross-magnetizing 14. One of the advantages of distributing the winding in alternators is to \_\_\_\_\_. A. Reduce harmonics B. Reduce the amount of copper C. Decrease the value of the voltage D. Improve voltage wave form 15. Distribution factor is the ratio of the emf's of \_\_\_\_\_\_\_. A. Distributed winding to concentrated winding B. Distributed winding to full pitch winding C. Full pitch winding to distributed winding D. Concentrated winding to distributed winding 16. Synchronization of alternators means \_\_\_\_\_\_\_\_. A. Connecting alternators in parallel B. Connecting alternators in series C. Transferring of load from one alternator to the other D. Adjusting the excitation of the alternators 17. In order to transfer the load from one alternator to another alternator when they are operating in parallel, \_\_\_\_\_\_\_\_. A. Field current is increased B. Field current is decreased C. Prime mover power input is increased D. None of these 18. Adjustment of field excitation on one of two alternators operating in parallel will\_\_\_\_\_\_\_\_\_. A. Increase its load B. Change its frequency C. Decrease its load D. Change its pf 19. Each of the two alternators operating in parallel are adjusted for unity power factor. Increasing the field current of one \_\_\_\_\_\_. A. Causes its power factor to become leading B. Causes its power factor to become lagging C. Changes its speed D. Increases its 20. Dampers in large alternators \_\_\_\_\_\_\_. A. Reduce voltage fluctuations B. Reduce frequency fluctuations C. Increase stability D. None of these 21. If the input to the prime mover of an alternator operating in parallel with another alternator is kept constant but its excitation is changed then \_\_\_\_\_\_\_\_\_. A. The reactive component of its output is changed B. The active component of its output is changed C. Its power factor will be the same D. The total load increases 22. The input power to the prime mover of an alternator is lost, but the alternator remains connected to the supply network and field supply is on. The alternator will \_\_\_\_\_\_\_. A. Get burned B. Behave as induction motor C. Behave as a synchronous motor and will rotate in the same direction D. Behave as a synchronous motor and will rotate in the reverse direction 23. Low speed large alternators are driven by \_\_\_\_\_\_\_\_. A. Steam turbines B. Hydraulic turbines C. Steam engines D. None of these 24. High speed large alternators are driven by \_\_\_\_\_\_. A. Diesel engines B. Dc motors C. Steam turbines D. Hydraulic turbines 25. The rotor of a turbo-alternator is made smooth cylindrical in order to reduce \_\_\_\_\_\_\_\_\_. A. Eddy current loss B. Windage losses C. Hysteresis loss D. Excitation losses 26. Alternators driven by \_\_\_\_\_\_ do not have a tendency to hunt. A. Diesel engines B. Hydraulic turbines C. Steam turbines D. None of these 27. Backward and forward motion of the rotor of an alternator about the stable position is called \_\_\_\_\_\_\_. A. Hunting B. Interference C. Vibration D. Disturbance 28. Prevents hunting in alternators. A. Damper or amortisseur winding B. Interpole winding C. Compensating winding D. None of these 29. The rating of an alternator is expressed in \_\_\_\_\_\_. A. KW B. KVAR C. KVA D. HP 30. The number of complete cycles generated in a 6 pole alternator in one revolution is \_\_\_\_\_\_\_\_. A. 3 B. 2 C. 4 D. 6 31. The speed in rps at which an 8 pole alternator should be driven to generate 60 cycles/sec is \_\_\_\_\_\_. A. 18 B. 15 C. 12 D. 9 32. In case of a 4 pole alternator, 1 mechanical degree corresponds to ­­­\_\_\_\_\_\_ electrical degrees. A. 8 B. 6 C. 2 D. 4 33. A 30 MVA, 15 KV alternator will have a per phase base impedance of \_\_\_\_\_ohms. A. 18 B. 9 C. 15 D. 7.5 34. In the armature winding of an alternator, the coil span falls short of full pitch by 60 electrical degrees. The pitch factor is \_\_\_\_\_\_\_. A. 0.866 B. 1 C. 0.5 D. 0.966 35. A 3 phase alternator has 3 slots/pole. The distribution factor of the winding is \_\_\_\_\_\_\_\_. A. 0.866 B. 0.5 C. 1 D. 0.707 **[ELECTROMAGNETIC INDUCTION]** 1. Whenever a conductor cuts magnetic flux, an emf is induced in the conductor. This is according to \_\_\_\_\_\_. A. Joule's law B. Faraday's law C. Coulomb's law D. Weber's law 2. The direction of the induced emf in a coil is such that it opposes its cause. This is according to \_\_\_\_\_\_\_. A. Joule's law B. Coulomb's law C. Lenz's law D. Ewing's law 3. The coefficient of coupling between two air core coils depends on \_\_\_\_\_\_. A. Mutual inductance and self inductances of the two coils B. Self inductances of the two coils only C. Mutual inductance of the two coils only D. None of these 4. While comparing magnetic and electric circuits, the flux of the magnetic circuit is compared with \_\_\_\_\_\_of the electric circuit. A. Emf B. Current C. Current density D. Conductivity 5. The effect of the inductance of a coil on a constant direct current is that \_\_\_\_\_\_\_\_\_\_. A. It strengthens the current B. It decreases the current C. It causes a higher voltage drop D. It does not affect the constant direct current 6. Air gap in the iron core of an inductor prevents \_\_\_\_\_\_. A. Hysteresis loss B. Flux change C. Transformer action D. Core saturation 7. The growth of current in an inductive circuit follows \_\_\_\_\_\_\_. A. Hyperbolic law B. Exponential law C. Linear law D. Ohm's law 8. The mutual inductance of two coils is maximum when the coils are \_\_\_\_\_\_\_. A. Touching each other B. Facing each other C. At right angles to each other D. Inclined at an angle of 45 degrees 9. Eddy current in an electrical machine is reduced by \_\_\_\_\_\_. A. Increasing the frequency of the field B. Laminating the core C. Using thick sheets of steel D. None of these 10. The measure of the ease to which a material allow the establishment of magnetic flux in it is called \_\_\_\_\_\_\_. A. Permittivity B. Conductivity C. Permeability D. Reluctivity 11. Hysteresis in the phenomenon of \_\_\_\_\_\_in a magnetic circuit. A. Lagging of magnetic flux density behind the magnetizing force. B. Setting up constant flux C. Lagging of magnetizing force behind the magnetic flux density D. None of these 12. The area of hysteresis loop will be least for \_\_\_\_\_\_\_. A. Wrought iron B. Silicon steel C. Soft iron D. Hard steel 13. The area of the plotted hysteresis loop of a magnetic material is the \_\_\_\_\_\_in that material. A. Eddy current loss B. Stray load loss C. Hysteresis loss D. None of these 14. Eddy current \_\_\_\_\_\_-. A. Is caused by a constant flux B. Is an independent current induced in the iron portion (core) of an electrical device or machine C. Causes loss in an electrical machine D. Both a and c 15. Property of a material in the circuit to oppose any change in current in the circuit. A. Impedance B. Conductance C. Resistance D. Inductance **[SINGLE PHASE MOTORS]** 1. For the same rating, a dc series motor costs \_\_\_\_\_\_\_single phase series motor. A. Less than B. More than C. About the same D. None of these 2. The least expensive fractional hp motor is \_\_\_\_\_\_\_. A. Capacitor start B. Split phase C. Shaded pole D. Universal 3. A capacitor-run single phase induction motor is essentially a \_\_\_\_\_\_\_. A. Simulated 3 phase induction motor B. A single phase motor with power factor correction C. A single phase motor with starting winding D. A simulated two phase induction motor 4. The starting torque of a capacitor start split phase induction motor is directly related to the angle -- α between its two stator winding currents by the relation \_\_\_\_\_\_. A. Sinα B. Cosα C. Tanα D. Sin α/2 5. A capacitor start single phase induction motor is switched on to the supply with its capacitor replaced by inductor of equivalent reactance value. It will \_\_\_\_\_\_\_\_\_. A. Start and run B. Start and then stall C. Not start D. None of these 6. If the centrifugal switch of a two value capacitor motor using two capacitors fails to open, then, A. Motor will not carry the load B. Electrolytic capacitor may suffer breakdown C. Motor will not come up to speed D. Line current will be high 7. Two value capacitor motor has recently found increased application as compressor motor in small home air conditioners because \_\_\_\_\_\_. A. It is quiet in operation B. It is comparatively cheaper C. It has almost non-destructible capacitor D. It has high power factor 8. One of the characteristics of a single phase induction motor is that it \_\_\_\_\_\_\_. A. Is not self starting B. Is self starting C. Requires only one winding D. Can rotate in one direction only 9. A repulsion motor is equipped with a \_\_\_\_\_\_. A. Slip rings B. Commutator C. Both slip rings and commutator D. Neither slip rings nor commutator 10. A repulsion-start induction run single phase motor runs as an induction motor only when \_\_\_\_\_\_. A. Brushes are shifted to neutral plane B. Shortcircuiter is disconnected C. Commutator segments are shortcircuited D. Connection of stator winding is reversed 11. In a repulsion motor brushes are connected A. To stator winding B. To the external supply C. To the starting winding D. Together by a jumper wire 12. If a dc series motor is operated on ac supply it will \_\_\_\_\_\_. A. Have poor efficiency B. Have poor power factor C. Spark excessively D. All of these 13. An outstanding feature of a universal motor is \_\_\_\_\_\_\_. A. Slow speed at all loads B. Highest horsepower/Kg ratio C. Poor performance on dc supply D. None of these 14. The speed of a universal motor can be reduced by \_\_\_\_\_\_. A. Brakes B. Belts C. Gearing D. Chains 15. The most common cause of brush sparking in a universal motor is \_\_\_\_\_\_. A. Shorted field winding B. Shorted armature winding C. Open armature winding D. All of these 16. In a shaded pole motor rotating magnetic field is produced by using \_\_\_\_\_\_. A. Shading coils B. Capacitor C. Salient poles D. Copper windings 17. By pushing and pulling the rotor of a motor, we can check its \_\_\_\_\_\_\_. A. Firmness of mounting B. Free shaft movement C. End play D. Side play 18. Which of the following causes motor overheating? A. Overload B. Shorted winding C. Worn or dry bearings D. All of these 19. Motor usually used as record players and tape recorders. A. Hysteresis B. Reluctance C. Shaded pole D. Universal 20. Motor usually used as timing and signaling devices. A. Hysteresis B. Shaded pole C. Reluctance D. Universal 21. Motor usually used as toys. A. Hysteresis B. Shaded pole C. Universal D. Split phase 22. Motor usually used as electric shaver. A. Split phase B. Capacitor C. Shaded pole D. Universal 23. Motor usually used as electric fan. A. Universal B. Capacitor run C. Capacitor start D. Two value capacitor 24. Motor usually used as portable tools. A. Shaded pole B. Universal C. Capacitor run D. Capacitor start 25. The direction of rotation of a universal motor can be reversed by \_\_\_\_\_. A. Reversing the field winding leads B. Reversing the armature winding leads C. Cannot be reversed D. Either a or b 26. The direction of rotation of the split phase or the capacitor start motor can be reversed by \_\_\_\_\_\_. A. Reversing the connection of the auxiliary (starting) winding B. Reversing the connection of the main winding C. Either a or b D. Cannot be reversed 27. The direction of rotation of a repulsion type motor can be reversed by \_\_\_\_\_. A. Moving the brushes in the direction of original rotation until rotation is reversed B. Moving the brushes in the direction opposite that of the original rotation until rotation is reversed. C. Either a or b D. Cannot be reversed 28. A single phase motor which can be operated using ac or dc source. A. Hysteresis B. Universal C. Reluctance D. Shaded pole 29. A single phase induction motor employs \_\_\_\_\_\_rotor. A. Wound B. Squirrel cage C. Either wound or squirrel cage D. None of these 30. Most of single phase induction motors are \_\_\_\_\_pole machines. A. 2 B. 8 C. 4 D. 6 31. The starting winding of a single phase induction motor has \_\_\_\_\_\_that of the main winding. A. Same number of poles as B. More poles than C. Less poles than D. None of these 32. In a single phase induction motor, speed sensitive centrifugal switch is connected in \_\_\_\_\_winding. A. Parallel with main B. Series with main C. Parallel with starting D. Series with starting 33. The purpose of starting winding in a single phase induction motor is to \_\_\_\_\_\_\_. A. Reduce losses B. Provide starting current C. Produce rotating flux in conjunction with the main D. Produce high starting power 34. The single phase shaded pole motor has \_\_\_\_\_\_. A. High power factor B. Squirrel cage rotor C. Wound rotor D. High starting torque 1. A. The frequency in the rotor is lowest at start and increases with increasing speed B. The frequency in the rotor decreases after start and increases again at full speed C. The frequency in the rotor is highest at start and decreases with increasing speed D. The frequency is the same at start and after start 2. A. Runs at a speed equal to the speed of stator field. B. Runs at a speed which is higher than the speed of stator field. C. Runs at a speed always lower than the speed of stator field. D. None of these 3. A. Increases with the increase in supply voltage B. Decreases with the increase in supply voltage C. Has no relation with the supply voltage D. None of these 4. A. The magnetizing current will decrease B. The power factor will decrease C. The core loss will increase D. The magnetizing current will increase 5. A. Decrease the starting power factor B. Achieve the maximum torque C. Limit the starting current D. Prevent noisy starting operation 6. A. It is constant in magnitude B. It rotates at synchronous speed C. It induces emf in the rotor conductors D. It is varying in magnitude 7. A. It is unity at standstill B. It has zero value at synchronous speed C. It can have negative value at no-load D. It determines the rotor emf frequency under running conditions 8. A. Synchronous B. Induction C. Compound D. Shunt 9. A. Faraday's law B. Lenz law C. Rotating magnetic field D. Flemings right hand rule 10. A. A pulsating and reversing magnetic field. B. A sinusoidally varying magnetic field. C. A rotating magnetic field of constant strength D. A rotating magnetic field of varying strength 11. A. Synchronous B. Static C. Rotor D. None of these 12. A. Line voltage B. Slip rings C. A centrifugal switch D. Magnetic induction 13. A. Interchange all the 3 line connections B. Interchange any two of the 3 line connections C. Reverse the polarity of the rotor circuit D. Increase the resistance of the rotor circuit 14. 15. A. Rotor frequency B. Rotor inductance C. Stator magnetic flux D. Mutual magnetic flux 16. A. Len'z law would be violated B. Rotor torque would then become zero C. Air friction prevents it to do so D. It would then become synchronous motor 17. A. Wound rotor induction motor B. Synchronous motor C. Squirrel cage rotor induction motor D. Either a or b 18. A. Reluctance motor B. Synchronous motor C. Squirrel cage rotor induction motor D. Wound rotor induction motor 19. A. Magnetizing current will increase B. Line current will increase C. Slip will increase D. Power factor will improve 20. A. It occurs beyond the full load torque B. Rotor power factor is unity C. Rotor resistance equals the variable rotor reactance. D. Rotor power factor is 70.7 percent 21. A. Short-circuiting slip rings B. Decreasing applied voltage C. Decreasing external resistance in rotor circuit D. None of these 22. A. 20 to 30 B. 5 to 15 C. 10 to 20 D. 2 to 5 23. A. It is cheaper B. It requires less maintenance C. External resistance can be inserted in the rotor circuit to control the speed D. Both a and b 24. A. Speed control is not required B. Less expensive motor is required C. High motor running resistance is required D. High starting torque is required 25. A. Dc series motor B. Dc shunt motor C. Dc compound motor D. Reluctance motor 26. A. Rotor windings are generally wye -- connected B. They are costly and require greater maintenance C. Slip rings are required on the rotor D. None of these 27. A. Independent of B. Inversely proportional to C. Directly proportional to D. None of this 28. A. Starting B. Full load C. No-load D. Half full load 29. A. Independent of B. Directly proportional to the square of C. Directly proportional to D. None of these 30. A. Inversely proportional to the supply voltage B. Inversely proportional to the square of the rotor reactance at standstill C. Inversely proportional to the rotor reactance at standstill D. None of these 31. A. High resistance B. Large slip C. High reactance D. Low resistance 32. A. To prevent cogging B. To have uniform torque C. To reduce motor hum D. All of these 33. A. Open -- circuited B. Short -- circuited C. Supplying a resistive load D. Supplying a reactance load 34. A. Open -- circuited B. Short -- circuited C. Supplying a resistance load D. Supplying a reactance load 35. A. Open -- circuited B. Short -- circuited C. Supplying a resistive load D. Supplying an impedance load 36. A. High inductance B. Low resistance C. Low inductance D. High resistance 37. A. Direct starting B. Auto-transformer starting C. Star-delta starting D. Primary resistance starting 38. A. Decreased at starting B. Increased during running C. Increased at starting D. None of the above 1. The steel for construction of transformer core must have \_\_\_\_\_\_\_. A. Low permeability and low hysteresis B. Low permeability and high hysteresis C. High permeability and low hysteresis D. High permeability and high hysteresis 2. The main function of the iron core in a transformer is to \_\_\_\_\_\_. A. Provide strength to the windings B. Decrease the hysteresis loss C. Reduce eddy current loss D. Decrease reluctance of the magnetic path 3. The maximum flux produced in the core of a transformer is \_\_\_\_\_\_\_. A. Directly proportional to the supply frequency B. Inversely proportional to the supply frequency C. Directly proportional to the primary number of turns D. Inversely proportional to the primary voltage 4. Ideal transformer assumptions do not include\_\_\_\_\_\_. A. Zero reactance of windings B. Zero resistance of windings C. No leakage flux D. No saturation of core 5. A static device that transfers ac electrical energy from one circuit to another without change in frequency. A. Transducer B. Transformer C. Oscillator D. Inverter 6. The working principle of a transformer is \_\_\_\_\_\_\_\_. A. Dynamic induction B. Static induction C. Mutual induction D. Self induction 7. The primary and secondary windings of a transformer are \_\_\_\_\_coupled. A. Electrically B. Physically C. Magnetically D. Electromagnetically 8. Transformer is used to change the values of \_\_\_\_\_\_\_. A. Frequency B. Power C. Power factor D. Voltage 9. Transformer cores are laminated in order to reduce \_\_\_\_\_\_\_. A. Eddy current loss B. Hysteresis loss C. Copper loss D. Both a and b 10. Transformer cores are made up of \_\_\_\_\_\_. A. Manganese steel B. Silicon steel C. Cobalt D. Carbon steel 11. Two things which are the same for primary and secondary of a transformer are \_\_\_\_\_\_\_. A. Resistances and leakage reactances B. Frequencies and copper losses C. Ampere turns and voltage per turn D. Currents and voltages 12. Eddy current loss in a transformer is reduced by laminating the core, the lamination being insulated from each other by \_\_\_\_\_\_. A. Varnish B. Mica C. Paper D. Rubber 13. The induced emf in the transformer secondary will depend upon \_\_\_\_\_\_. A. Maximum flux and supply frequency only B. Frequency of the supply only C. Number of turns in the secondary only D. Maximum flux, supply frequency and number of secondary turns 14. At every instant the direction of the secondary current in a transformer must be such as to oppose any change in flux. This is in accordance with \_\_\_\_\_\_. A. Faraday's law B. Joule's law C. Lenz law D. Coulomb's law 15. The magnitude of the mutual flux in a transformer is \_\_\_\_\_\_. A. Low at low loads B. High at high loads C. Same at all loads levels D. High at low loads 16. Concentric windings are used in core type transformer with \_\_\_\_\_\_. A. High voltage winding placed near the core B. Low voltage winding placed near the core C. Low voltage winding placed on the outer side D. High voltage winding placed between parts of the low voltage winding 17. The no-load current of a transformer in terms of full load current is usually \_\_\_\_\_\_. A. 3 to 9% B. 9 to 12% C. 1 to 3% D. 12 to 20% 18. What type of core is used for a high frequency transformer? A. Closed iron core B. Open iron core C. Aluminum core D. Air core 19. The eddy current loss in a transformer is directly proportional to the \_\_\_\_\_\_. A. Square of the thickness of core lamination B. Thickness of core lamination C. The supply frequency D. The flux density in the core 20. What is the common method of cooling power transformer? A. Air cooling B. Oil cooling C. Air-blast cooling D. Natural cooling 21. The use of higher flux density in transformer design \_\_\_\_\_\_. A. Increases the weight per KVA B. Increases the weight per KW C. Decreases the weight per KVA D. Decreases the weight per KW 22. The transformer oil is used in transformers provide \_\_\_\_\_\_. A. Cooling and lubrication B. Insulation, cooling, and lubrication C. Insulation and lubrication D. Insulation and cooling 23. Power transformers are design to have maximum efficiency at \_\_\_\_\_\_. A. No-load B. Half load C. Near full load D. Little more than full load 24. The efficiency of a transformer is normally in the range of \_\_\_\_\_. A. 50 to 70% B. 90 to 98% C. 60 to 75% D. 80 to 90% 25. Distribution transformers have good all-day efficiency due to \_\_\_\_\_\_\_. A. Low core loss B. Low copper loss C. Low core and low copper loss D. None of these 26. In a transformer, the purpose of the "breather" is to \_\_\_\_\_\_\_. A. To take insulating oil from conservator B. To extract moisture of the air C. To provide cooling to the winding D. To provide insulation to the winding 27. Conservator of a transformer consists of \_\_\_\_\_\_\_. A. Overload protection B. Drum placed at the bottom of the tank to store oil C. An air-tight metal drum fixed at the top of the tank to store oil D. None of these 28. In a power transformer the winding which is nearer to the iron core of the transformer is \_\_\_\_\_\_. A. High voltage winding B. May the high voltage or low voltage winding C. Low voltage winding D. None of these 29. A good transformer oil should be absolutely free from \_\_\_\_\_\_. A. Sulphur B. Moisture C. Alkalies D. All of these 30. The transfer of energy from primary to the secondary of the transformer takes place due to \_\_\_\_\_\_\_\_. A. The flux linkages between the two windings B. The difference in number of turns between the windings C. The changing current in the two windings D. None of these 31. The no-load primary input power is practically equal to the iron or core loss in the transformer because \_\_\_\_\_\_\_. A. Secondary current is small B. Primary current is small C. Both currents are small D. None of these 32. Which of the statements given below is true about auto-transformer? A. It can only step down the voltage B. It is most suitable for power transformation C. It has only one winding D. It has two separate windings 33. What is the typical use of an auto-transformer? A. Toy transformer B. Control transformer C. Isolating transformer D. Variable transformer 34. When the primary of a transformer is connected to a dc supply, \_\_\_\_\_\_. A. Primary draws small current B. Core losses are decreased C. Primary may burn out D. Primary leakage reactance is increased 35. The primary leakage flux links the/both \_\_\_\_\_. A. Secondary winding turns only B. Primary winding turns only C. Primary and secondary windings D. None of these 36. The effect of leakage flux in a transformer is to \_\_\_\_\_\_\_. A. Increase copper losses B. Decrease copper losses C. Cause voltage drops in the windings D. None of these 37. Core of large transformers are built up to nearly circular cross-section in order to reduce\_\_\_\_\_\_\_. A. Leakage reactance B. Eddy current loss C. Iron or core loss D. Copper loss 38. In the open circuit or no-load test on a transformer, instruments are inserted on \_\_\_\_\_\_\_\_\_\_. A. The low voltage winding B. The high voltage winding C. Either low or high voltage winding D. None of these 39. The open circuit or no-load test on a transformer gives \_\_\_\_\_\_\_\_\_. A. The copper loss B. The iron loss C. The friction loss D. The total losses 40. In a short circuit test on a transformer, we generally short circuit \_\_\_\_\_\_. A. High voltage winding B. Either the high voltage or low voltage winding C. Low voltage winding D. None of these 41. The short circuit test on a transformer gives the \_\_\_\_\_\_\_. A. Total losses B. Friction loss C. Iron loss D. Copper loss 42. The efficiency of a transformer will be maximum when \_\_\_\_\_\_\_\_\_. A. Copper loss equals core loss B. Leakage reactances of the two windings are equal C. Resistances of the two windings are equal D. None of these 43. What is meant by flash point of the transformer oil? A. Temperature at which the oil will begin to decompose B. Ignition temperature of oil C. Temperature at which the oil will begin to ionize D. None of these 44. Which material is used as moisture absorber in the transformer breather? A. Calcium carbide B. Calcium sulfide C. Calcium chloride D. Calcium carbonate 45. What relay is used for transformers? A. Mertz relay B. Mho relay C. Translay relay D. Buchholz relay 46. The transformer that should never have its secondary open circuited when primary is energized is called \_\_\_\_\_\_\_\_. A. Power transformer B. Current transformer C. Potential transformer D. Control transformer 47. Before removing the ammeter from a current transformer, its secondary must be short-circuited in order to avoid \_\_\_\_\_\_\_. A. Excessively heating of the core B. High secondary emf C. Increase in core loss D. All of these 48. Current transformers for meters and relays usually have \_\_\_\_\_\_. A. 10A secondaries B. A 10:1 ratio C. 5A secondaries D. A 1:1 ratio 49. The load of an instrument transformer consisting of delicate moving elements of meters is termed as \_\_\_\_\_\_\_. A. Instrument impedance B. Meter load C. Burden D. Transformer power 50. Dust should never be allowed to accumulate on the windings and core of a dry type transformer because it \_\_\_\_\_\_\_\_. A. Tends to corrode metal surface B. May short circuits the windings C. Absorbs oil and grease D. Reduces dissipation of heat 51. The most common cause of contamination by water of oil used in transformer located indoor is \_\_\_\_\_\_\_. A. Condensation of moisture from air in the upper part of the tank. B. Leaky bushings C. Decomposition of organic matter in oil D. Use of filter blotters 52. The part of the transformer which is most subject to damage from overheating is \_\_\_\_\_\_\_\_\_. A. Frame or case B. Iron core C. Winding insulation D. Copper winding 53. The essential element or condition for parallel operation of two single phase transformers is that they should have the same \_\_\_\_\_\_\_\_. A. Frequency rating B. Polarity C. Phase sequence D. Voltage ratio 54. Of the following statements concerning parallel operation of transformer, the one incorrect is that transformer must \_\_\_\_\_\_\_\_\_. A. Have equal voltage ratings B. Have same ration of transformation C. Be operated at the same frequency D. Have equal KVA ratings 55. The following are advantages of a 3 phase transformer over 3 single phase bank of transformers of the same 3 phase capacity, except \_\_\_\_\_\_\_\_\_. A. Less cost and less weight B. Requires less space C. Less cost in repairs D. Somewhat higher efficiency 56. What is the possible minimum, angular shift between the voltages of wye-connected primary winding and delta-connected secondary winding? A. 60 degrees B. 30 degrees C. 120 degrees D. 150 degrees 57. What causes transformer hum? A. The magneto-restriction of the core material due to the varying magnetic flux B. The slight movement of the coils due to varying attractive magnetic forces. C. The slight movement of the coil insulation due to varying electric potentials. D. The slight relative motion between primary and secondary windings due to transfer of varying power. 58. A transformer used to measure high current and also used in relaying is called \_\_\_\_\_\_transformer. A. Isolating B. Current C. Potential D. Control 59. A transformer used to measure high voltage and also used in relaying is called \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_transformer. A. Isolating B. Control C. Potential D. Current 60. The two errors in an instrument transformer are \_\_\_\_\_\_\_. A. Ratio and impedance errors B. Phase angle and impedance errors C. Power factor and ratio errors D. Ratio and phase angle errors **[SYNCHRONOUS MOTOR]** 1. A synchronous motor has \_\_\_\_\_\_\_\_\_\_. A. Slight drop in speed at full load B. High speed at low torque C. Low speed at high torque D. Constant speed 2. Damper (amortisseur)winding in a synchronous motor \_\_\_\_\_\_\_. A. Serves to start the motor B. Prevents hunting of the motor C. Improves power factor of the motor D. Both a and b 3. A synchronous motor when running has slip of \_\_\_\_\_\_\_%. A. 2 B. 0 C. 5 D. 1 4. The synchronous speed of 10 pole, 60 Hz 3 phase synchronous motor is \_\_\_\_\_\_\_rpm. A. 900 B. 500 C. 720 D. 600 5. A synchronous motor is capable of being operated at \_\_\_\_\_\_\_. A. Lagging power factor only B. Leading power factor only C. Lagging or leading pf D. None of these 6. When the stator winding of a synchronous motor is connected in such a way that the number of poles are half made, the speed of the rotor \_\_\_\_\_\_\_. A. Tends to become zero B. Decreases to one half of the original value C. Remains the same as the original value D. Increases to two times the original value 7. Synchronizing power of a synchronous machine is \_\_\_\_\_\_\_. A. Equal to the synchronous reactance B. Inversely proportional to the synchronous reactance C. Directly proportional to the synchronous reactance D. None of these 8. An over -- excited synchronous motor has \_\_\_\_\_\_\_\_\_\_\_. A. Leading pf B. Lagging pf C. Unity pf D. Leading or lagging pf 9. When the excitation of an unleaded salient pole synchronous motor is suddenly disconnected, then \_\_\_\_\_\_\_\_. A. It runs at lower speed B. It runs at higher speed C. The motor stops D. It run at the same speed 10. A 3 phase, 60 Hz, 4 pole synchronous motor has a torque angle of 10 electrical degrees. The torque angle in mechanical degrees is \_\_\_\_\_\_\_\_\_\_\_\_. A. 4 B. 20 C. 10 D. 5 11. A 3 phase synchronous motor is running clockwise. In case the direction of its field current is reversed, then the \_\_\_\_\_\_\_\_\_\_\_. A. Motor will continue to run in the same direction. B. Motor will run in the reverse direction C. Motor will stop D. Winding of the motor will burn 12. In a synchronous motor, the synchronizing power comes into action when \_\_\_\_\_\_\_\_\_\_\_. A. Rotor speed is equal to synchronous speed B. Rotor speed is less than the synchronous speed C. Rotor speed is more than the synchronous speed D. Rotor speed is either less or more than the synchronous speed. 13. The minimum current of the synchronous motor corresponds to operation at \_\_\_\_\_\_\_\_\_\_. A. 0.8 pf leading B. Unity pf C. Zero pf leading D. None of these 14. If the field of a synchronous motor is under-excited, then its pf is \_\_\_\_\_\_\_\_. A. Leading B. Unity C. Lagging D. More than unity 15. The rotor of a synchronous motor is excited with direct current when the motor \_\_\_\_\_\_\_\_\_\_\_\_\_. A. Is at standstill B. Approaches synchronous speed C. Approaches one half of the synchronous speed D. None of these 16. When the synchronous motor runs at synchronous speed, the voltage induced in the damper winding is \_\_\_\_\_\_\_\_\_\_. A. Minimum B. Maximum C. One half of maximum D. Zero 17. In order to reverse the direction of rotation of a 3 phase synchronous motor \_\_\_\_\_\_\_\_\_\_\_\_\_. A. Interchange the connection of any two lines B. Reduce dc excitation to zero C. Change the supply frequency D. Change the number of poles 18. The speed of a synchronous motor can be changed by varying the \_\_\_\_\_\_\_\_\_. A. Mechanical load B. Supply frequency C. Field excitation D. None of these 19. The pull -- out torque of a synchronous motor will \_\_\_\_\_\_\_\_\_\_\_\_as the field excitation is increased. A. Decrease B. Remains the same C. Increase D. None of these 20. The change of load on a synchronous motor will not result in the change of \_\_\_\_\_\_\_\_\_\_\_. A. Armature current B. Torque angle C. Power factor D. Speed 21. For a given load, the normal field excitation of a synchronous motor is that which gives \_\_\_\_\_\_\_\_\_\_\_\_\_power factor. A. Unity B. 0.8 leading C. 0.8 lagging D. None of these 22. An over-excited synchronous motor behaves as \_\_\_\_\_\_\_\_\_\_\_\_\_\_. A. A resistor B. A capacitor C. An inductance D. None of these 23. An under-excited synchronous motor behaves as \_\_\_\_\_\_\_\_\_\_\_\_\_. A. A resistor B. A capacitor C. An inductor D. None of these 24. When a synchronous motor is on no load, the torque angle is about \_\_\_\_\_\_\_\_\_\_\_\_electrical degrees. A. 45 B. 30 C. 90 D. 0 25. The mechanical power developed by a synchronous motor is independent of \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_. A. Applied stator voltage B. Field excitation C. Speed D. Torque angle 26. A synchronous condenser is a synchronous motor \_\_\_\_\_\_\_\_\_\_\_\_. A. Running at full load B. Running at no load C. Running at half full load D. None of these 27. For the same horsepower output, the efficiency of a 3 phase synchronous motor is \_\_\_\_\_\_\_\_that of a 3 phase induction motor. A. Greater than B. Lesser than C. About the same D. None of these 28. For the same active power consumed, a 3 phase synchronous motor draws \_\_\_\_\_\_\_\_\_that of a 3 phase induction motor. A. More induction motor B. Less apparent power than C. The same apparent power D. None of these 29. Synchronous motors are generally used in applications requiring \_\_\_\_\_\_\_\_. A. In frequent starting B. Variable speed C. Frequent application D. Sudden application of heavy loads 30. The speed of a 3 phase synchronous motor connected to a 60 Hz supply is 900 rpm. The number of poles is \_\_\_\_\_\_\_\_\_\_. A. 12 B. 6 C. 8 D. 10t 1. Load factor is \_\_\_\_\_\_\_\_\_\_\_\_\_\_. A. Maximum demand/connected load B. Average load/maximum demand C. Average load/installed capacity D. Maximum demand/average load 2. For economy in power generation, \_\_\_\_\_\_\_\_\_\_. A. Load factor should be high B. Diversity factor should be high C. Plant use factor should be high D. Load factor and diversity factor should below 3. A load curve is a plot of \_\_\_\_\_\_\_\_\_\_. A. Load versus time B. Load versus cost of power C. Load versus current D. Load versus generation capacity 4. During summer months, the increased load is due to \_\_\_\_\_\_\_\_\_. A. Increased water supply B. Vacations in institutions C. Increased business activities D. Increased use of fans and air conditioners 5. Load due to a ceiling fan is nearly \_\_\_\_\_\_\_\_\_\_watts. A. 40 to 80 B. 100 to 200 C. 20 D. 250 to 2000 6. Which of the following utility item has the highest power rating? A. Mixer B. Ceiling fan C. Electric iron D. Refrigerator 7. A power plant supplying energy to a city will usually experience peak demand from \_\_\_\_\_\_\_\_\_\_\_\_\_. A. Midnight to early morning B. 8 AM to 12 NOON C. 2 PM to 6PM D. 6 PM to 12 PM 8. Capital cost per MWh is highest in case of \_\_\_\_\_\_\_\_\_\_\_. A. Steam power plant B. Diesel engine power plant C. Nuclear power plant D. Hydroelectric power plant 9. A diesel power plant is best suited as \_\_\_\_\_\_\_\_\_\_\_\_. A. Standby plant B. Base load plant C. Peak load plant D. General purpose plant 10. A gas turbine power plant usually suits for \_\_\_\_\_\_\_\_\_\_. A. Casual run B. Base load operation C. Peak load operation D. None of these 11. Which power plant cannot have a single unit of 100MW? A. Hydro -- electric power plant B. Steam power plant C. Diesel power plant D. Nuclear power plant 12. The useful life of a diesel engine in a power plant is expected to be \_\_\_\_\_\_\_\_\_\_\_\_years. A. 5 B. 50 C. 8 D. 15 13. Which of the following power plants is to have the longest expected life? A. Steam B. Diesel C. Hydro-electric D. All have the same life 14. A nuclear power plant is invariably used as a \_\_\_\_\_\_\_\_\_. A. Base load plant B. Peak load plant C. Standby plant D. Spinning reserve plant 15. During load shedding \_\_\_\_\_\_\_\_. A. System voltage is reduced B. Some loads are switched off C. System power factor is changed D. None of these 16. In a steam power plant which component needs maximum maintenance attention? A. Turbine B. Condenser C. Boiler D. Water treatment area 17. Which of the following relations is not correct? A. Capacity factor = Utilizaton factor x load factor B. Average load = load factor x maximum demand C. Maximum demand = connected load x demand factor D. None of these 18. Low utilization factor of a power plant indicates that the plant is \_\_\_\_\_\_\_\_\_\_\_\_\_. A. Used for base load only B. Under maintenance C. Used for standby purposes only D. Used for peak load as well as base load 1. a relay in which the measurement is performed by a stationary circuit and which has no moving parts is called \_\_\_\_\_\_\_\_\_\_\_. A. Static relay B. Differential relay C. Time relay D. Instantaneous relay 2. For high voltage ac circuit breakers, the rated short circuit current is passed for \_\_\_\_\_\_\_\_\_\_seconds. A. 0.1 B. 20 C. 3 D. 30 3. Which of the following is not a type of contactor for circuit breakers? A. Vacuum B. Pneumatic C. Electro-pneumatic D. Electro-magnetic 4. Interrupting medium in a contactor for circuit breakers? A. Air B. SF6 gas C. Oil D. Any of these 5. Which of the following circuit breakers has the lowest voltage range? A. Air blast B. SF6 C. Air break D. Tank type oil 6. Which of the following materials is not used in extinguishing the arc in case of a circuit breaker? A. Water B. Air C. Vacuum D. SF6 7. The transient voltage that appears across the contacts of a circuit breaker at the instant of arc extinction is called\_\_\_\_\_\_\_\_\_\_\_. A. Restriking voltage B. Recovery voltage C. Supply voltage D. Peak voltage 8. A relay used for protection of motors against overload is \_\_\_\_\_\_\_\_. A. Thermal relay B. Impedance relay C. Buchholz relay D. Magnetic relay 9. The number of cycles in which a high speed circuit breaker can complete its operation is \_\_\_\_\_\_\_\_\_\_. A. 3 to 8 B. 20 to 30 C. 10 to 18 D. 40 to 50 10. A material best suited for manufacturing of fuse wire is \_\_\_\_\_\_\_\_\_. A. Silver B. Copper C. Lead D. Aluminum 11. In a circuit breaker, the current which exist at the instant of contact separation is called \_\_\_\_\_\_\_\_. A. Interrupting current B. Restriking current C. Surge current D. Recovery current 12. A Merz-price protection is suitable for \_\_\_\_\_\_. A. Transformers B. Feeders C. Alternators D. Transmission lines 13. Interrupting capacity of a circuit breaker is usually expressed in \_\_\_\_\_\_. A. MVA B. Amperes C. Volts D. MW 14. Which of the following contact point metals has the highest melting point? A. Gold B. Silver C. Tungsten D. Copper 15. Sparking occurs when a load is switched off because the circuit has \_\_\_\_\_\_\_\_. A. High inductance B. High resistance C. High capacitance D. None of these 16. Sparking between contacts can be reduced by \_\_\_\_\_\_\_\_. A. Inserting a capacitor in parallel with the contacts B. Inserting resistance in the line C. Inserting a capacitor in series with the contacts D. None of these 17. An automatic device that operates at present values is called \_\_\_\_\_\_\_. A. Relay B. Fuse C. Mercury switch D. Contactor 18. The power factor of the arc in a circuit breaker is \_\_\_\_\_\_\_\_. A. Unity B. Zero C. Lagging D. Leading 19. Flame proof switch gears are usually preferred in \_\_\_\_\_\_\_\_. A. Mines B. Substations C. High MVA capacity circuits D. None of these 20. Air used in air blast circuit breaker \_\_\_\_\_\_\_\_\_. A. Must have least carbon dioxide B. Must be ionized C. Must have oil mist D. Must be free from moisture 21. In a circuit breaker, the time duration from the instant of fault to the instant of energizing of the trip coil is known as \_\_\_\_\_\_\_\_\_. A. Protective time B. Operation time C. Lag time D. Lead time 22. In a circuit breaker, the time duration from the instant of the fault to the extinction of the arc is known as \_\_\_\_\_\_\_\_. A. Total cleaning time B. Operation time C. Lead time D. Lag time 23. In a circuit breaker, the time duration from the instant of the fault to the instant of closing of contacts is known as\_\_\_\_\_\_\_\_. A. Reclosing time B. Recycle time C. Gross time D. Total time 24. For a high speed circuit breaker the total clearing time is nearly \_\_\_\_\_\_\_. A. 1 to 2 cyles B. 10 to 15 cycles C. 5 to 10 cycles D. Less than 50 cycles 25. For a circuit breaker, "break" time is \_\_\_\_\_\_. A. Same as operating time B. Opening time plus arc duration C. Opening time plus arc duration plus resistor current duration D. None of these 26. Which relay is used for feeders? A. Translay relay B. MHO relay C. Merz price relay D. Buchholz relay 27. Which relay is used for transmission lines? A. MHO relay B. Merz price relay C. Translay relay D. Buchholz relay 28. The value of fault current depends on \_\_\_\_\_\_\_. A. Total impedance up to the fault B. Voltage at the faulty point C. Both a and b D. None of these 29. The advantage of grounding the neutral is \_\_\_\_\_\_\_. A. Simplified design of ground fault protection B. Freedom from persistent arcing ground C. Over voltages due to lightning is discharged to the ground D. All of these 30. Over voltages surges in a power system may be caused by \_\_\_\_\_\_. A. Lightning B. Resonance C. Switching D. Any of these 31. The protection against over voltage due to lightning is provided by \_\_\_\_\_\_\_. A. The use of surge arrester B. Low tower footing resistance C. The use of overhead ground wires D. Any of these 32. A fuse is normally a \_\_\_\_\_\_\_. A. Current limiting device B. Voltage limiting device C. Power limiting device D. Power factor correcting device 33. Which of the following is a conducting medium for electric current? A. Low temperature gas B. High temperature gas C. Dissociated gas D. Plasma 34. In circuit breakers the contact space is ionized by \_\_\_\_\_\_\_. A. Thermal ionization of gas B. Thermal emission from surface of contacts C. Field emission from the surface of contacts D. Any of these 35. Which of the following are air break switching devices? A. Isolator B. Ground switch C. Limiting switch D. All of these 36. Which of the following is the demerit of SF6 circuit breaker? A. Sealing problem of gas B. Influx of moisture in the gas system is dangerous C. Deterioration of quality of circuit breaker affects reliability of the circuit breaker D. All of these 37. The material used for bus bars should have \_\_\_\_\_. A. Low resistivity B. Low cost C. Higher softening temperature D. All of these 38. Fuse in motor circuit provides \_\_\_\_\_\_\_. A. Short circuit protection B. Overcurrent protection C. Open circuit protection D. None of the above 39. The disadvantage of an ungrounded system is \_\_\_\_\_\_. A. Frequent arcing grounds B. Difficult ground fault relaying C. Voltage oscillation D. All of these 40. Series reactors are installed at strategic locations of a power system in order to \_\_\_\_\_\_\_. A. Bring down the fault level within the capacity of the switchgear B. Directly pass the fault current to ground C. Pass neutralizing surges of opposite nature D. Discharge the capacitor