EE Objective Questions (Current Electricity) PDF

CURRENT ELECTRICITY 1. What are the minimum requirements to cause the flow of current? A. A voltage source, an ammeter, a conductor conductor and an insulator B. A voltage voltage source, a switch and a resistor C. A voltage...

CURRENT ELECTRICITY 1. What are the minimum requirements to cause the flow of current? A. A voltage source, an ammeter, a conductor conductor and an insulator B. A voltage voltage source, a switch and a resistor C. A voltage source and a conductor D. A voltage voltage source, a conductor and an insulator 2. Out of the following, select the best conductor of electricity. A. Graphite B. China clay C. Porcelain D. None of these 3. Which of the following statements is correct? A. The 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 t he materials is independent of the temperature. D. The resistance of conductor is the hindrance by by which the conductor conductor opposes the the flow of the current. 4. Resistance of a conductor increases when A. its length increases B. its area increases C. both length and area increases D. specific resistance is kept constant 5. The specific resistance ρ depends upon A. The area of cross-section and the length of the conductor B. The material of the conductor, its area of cross-section and length C. The nature of the material of the conductor conductor only D. The area area of cross-section of the conductor 6. The specific resistance ρ is defined as A. resistance of a conductor which has a length of 1 m and cross-section of 1 m2 at 20oC B. resistance of any conductor at 25oC C. resistance of any conductor at 20oC D. resistance of a conductor which has a length of 1 m and cross-section of 1 cm2 at 20oC 7. The resistance of a conductor, when its temperature is increased A. remains constant B. increases C. varies D. decreases 8. It was experimentally found by James Prescott Joule that the heat produced in a current carrying conductor is proportional to A. the square of the current B. square of resistance C. the current D. inversely proportional to time 9. The value of Joule’s mechanical equivalent of heat, J, is equal to A. 4.2 calories per Joule B. 2.4 Joules per calorie C. 4.2 Joules per calorie D. 4.2 Joules A_Compilation_of_Objective_ A_Compilation_of_Objective_Type_Questions_i Type_Questions_in_Electrical_Engi n_Electrical_Engineering neering 1 of 94  CURRENT ELECTRICITY 10. Temperature coefficient of a conductor is defined as the A. increase in resistance per ohm per degree centigrade B. increase in resistance per degree centigrade C. increase in resistance per degree absolute D. decrease in resistance per ohm per degree centigrade centigrade 11. When current flows in a conductor, heat is produced because A. heat α I2 B. of electronic collision C. of interatomic collision D. of Joule’s law 12. Heating effect of current has undesirable side effect in A. electric oven B. electric iron C. immersion heater D. vacuum cleaner 13. The resistance of carbon (filament in carbon-filament lamps) when its temperature is decreased A. increases B. decreases C. remains the same D. increases enormously 14. The curve representing Ohm’s law is A. a parabola B. linear C. sine function D. a hyperbola 15. The condition in Ohm’s law is that A. ratio V/I should be constant B. current should be proportional to voltage C. the temperature should remain constant D. the temperature should vary 16. Ohm’s law does not apply to A. conductors B. conductors when there is change in temperature C. semiconductor D. a.c. circuit 17. Ohm’s law is applicable to A. electric arc B. rectifying devices C. gas discharge lamps D. none of these 18. Ohm’s law can be applied with certain reservations to A. rectifying devices B. semiconductors C. electrolytes D. thermionic valves 19. The presence of an electric current is made known by A. flashing B. effects produced C. cracking D. electric shock 20. An electric current can neither be _______ _______ nor _______. A. felt, seen B. seen, touched C. seen, produced any effect D. produced, felt A_Compilation_of_Objective_ A_Compilation_of_Objective_Type_Questions_i Type_Questions_in_Electrical_Engi n_Electrical_Engineering neering 2 of 94  CURRENT ELECTRICITY 21. The presence of the current is only made known by the effect it produces. Three important effects are A. heating, electric shock and generation B. generation, chemical and electric shock C. heating, magnetic and electric shock D. heating, magnetic and chemical 22. Voltage applied across a circuit, circuit, acts as A. mass of electrons B. negative ions C. a component of current D. a force 23. In a series circuit the current is A. constant B. always zero C. proportional to the resistance D. different in different resistors 24. In a parallel circuit the potential difference across the resistance A. varies B. is different from the applied voltage C. is sometimes constant D. is always constant 25. The resistance R1 and R2 are connected in parallel. The ratio of values of resistance R 1 : R 2 is 4 : 1. The currents in R1 : R2 will be equal to A. 1 : 4 B. 1 : 1 C. 4 : 1 D. 4 : 4 26. A resistance of 4 ohms is connected across 100 V supply. When another resistor ‘R’ ohms is connected in parallel with 4 ohms, the total current taken from supply was found to be 50 A. The value of resistance ‘R’ is A. 2 ohms B. 3 ohms C. 5 ohms D. 4 ohms 27. The voltage applied across an electric press was reduced by 50%. The power consumed by the press will be reduced by A. 25% B. 75% C. 60% D. 50% 28. Two electric presses are connected in parallel. The resistance of the first press is 100 ohms and that of the second is 300 ohms. The total current taken by both the presses is 4 A. The ratio of current taken by first : second will be equal to A. 2 : 3 B. 1 : 3 C. 3 : 1 D. 1.2 : 3 29. Three elements having conductance G1, G2 and G3 are connected in parallel. Their combined conductance will be 1 A. G1 + G2 + G3 B. G1 + G2 + G3 G1 G 2 + G 2 G 3 + G 3 G1 1 C. D. G1 + G 2 + G 3 1 1 1 + + G1 G 2 G 3 30. Four resistances R 1, R 2, R 3 and R4 are connected in series against 220 V supply. The resistances are such that R1 > R2 > R3 > R4. The least power consumption will be in A. resistor R1 B. resistor R4 C. resistor R3 D. resistor R2 A_Compilation_of_Objective_ A_Compilation_of_Objective_Type_Questions_i Type_Questions_in_Electrical_Engi n_Electrical_Engineering neering 3 of 94  CURRENT ELECTRICITY 31. When current flows through heater coil it glows but supply wiring does not glow because A. supply wiring is covered with insulation layer B. current through supply line flows at slower speed C. supply wires are made of superior material D. resistance of heater coil is more than that of supply wires 32. Resistors commonly used in power circuits are A. carbon resistors B. etched circuit resistors C. wire wound resistors D. deposited metal resistors 33. International ohm is defined in terms of resistance of A. a column of mercury B. a cube of carbon C. unit length of metal wire D. a cube of copper 34. Which of the following has negative coefficient of resistance? A. wire wound resistor B. non-metals C. thermistor D. metals 35. The current carrying capacity of the fuse material depends on A. length B. material C. cross-sectional area D. all of these A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 4 of 94  MAGNETISM AND ELECTROMAGNETISM 1. A natural magnet is called A. steel B. lodestone C. magnetism D. soft iron 2. A magnet is able to attract A. iron, aluminum and brass B. iron, cobalt and zinc C. iron, copper and nickel D. nickel, cobalt and steel 3. Externally, magnetic line of force travels A. south to north B. north to south C. negative to positive D. in both directions 4. A material commonly used for shielding or screening magnetism is A. brass B. aluminum C. copper D. soft iron 5. The magnetism that remains in a magnet after the magnetizing force has been removed is called A. permeability B. induction C. residual D. saturation 6. Iron becomes magnetized by induction when it is A. heated B. suspended east and west C. near to one end of a magnet D. treated with some chemicals 7. Magnetic lines of force are called A. hysteresis B. current C. flux D. magnetomotive force 8. The force between two magnetic poles varies with distance between them. The variation is A. in direct proportion to the distance B. in inverse proportion to the distance C. in direct proportion to the square of the distance D. in inverse proportion to the square of the distance 9. The magnetic potential in a magnetic circuit can be measured in terms of A. farads B. M.M.F. C. coulombs D. none of these 10. Permeance is analogous to A. conductance B. resistance C. reluctance D. none of these 11. The permeability of a material means A. strength of permanent magnet B. strength of an electromagnet C. the magnetization left in the iron after exciting field has been removed D. the conductivity of a material for magnetic lines of force 12. When the magnetic flux (φ) and the area (A) under its influence are known, the magnetic flux density (B) can be given as φ A. B = φA B. = A C. B= D. B = φA 2 φ A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 5 of 94  MAGNETISM AND ELECTROMAGNETISM 13. The relative permeability µr is given by B A. B. H µ0 µ0 C. D. µ H 14. Relative permeability of a material is given by (K is susceptibility of the material) A. 1 + µ 0K B. + µ0 C. 1+ C. µ 0H K 15. The relative permeability of paramagnetic substance is A. slightly less than 1 B. equal to 1 C. slightly greater than 1 D. very much greater than 1 16. The value of permeability for the free space is A. 4 x 10–7 Hm–1 B. 4 x 10–7 Hm–1 1 C. 4π x 107 Hm–1 D. × 10 − 7 Hm −1 4π 17. The magnetization in any magnetic material appears as a result of A. electrons orbital motion B. electron spin C. spin of the nucleus about its axis D. all of these 18. The sum of the magnetic moments in unit volume of the solid is called A. field strength B. magnetization C. permeability D. susceptibility 19. Which of the following materials does not have permanent magnetic dipole A. paramagnetic B. antiferromagnetic C. diamagnetic D. ferrimagnetic 20. Interaction between the neighboring dipoles is negligible in case of a A. paramagnetic material B. diamagnetic material C. antiferromagnetic material D. ferrimagnetic material 21. Each ferromagnetic material has characteristic temperature above which its properties are quite different from those below that temperature. This temperature is called A. transition temperature B. Faraday’s temperature C. demagnetization temperature D. Curie temperature 22. The relative permeability µ for iron is A. 5000 B. 7000 C. 3000 D. 1000 23. Which of the following material is used for making permanent magnets A. carbon steel B. platinum cobalt C. Alnico V D. All of these A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 6 of 94  MAGNETISM AND ELECTROMAGNETISM 24. Which of the following has the highest value of relative permeability µr? A. iron B. supermalloy C. Mu-metal D. 4% Si – Fe 25. Ferrimagnetic materials generally behave as a A. semiconductor B. conductor C. insulator D. any of A, B, or C 26. Transformer cores operating at microwave frequency ranges are generally made u p of A. ferrites B. silicon steel C. supermalloy D. alnico V 27. The magnetic materials which can be easily magnetized in both directions are known as A. soft magnetic materials B. hard magnetic materials C. low hysteresis loss materials D. high hysteresis loss materials 28. Eddy current loss can be minimized by A. decreasing the resistance of magnetic medium B. increasing the resistance of magnetic medium C. decreasing the permeability of magnetic medium D. none of the above A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 7 of 94  ELECTROMAGNETIC INDUCTION 1. The coefficient of self-inductance of a coil is defined as A. NI / φ B. φ C. φ / NI D. φI / N 2. Which of the following statement is incorrect? A. Whenever the flux linking with the coil or circuit changes the emf is produced. B. The direction of dynamically induced emf can be determined by Flemming’s right hand rule. C. Coefficient of coupling for tightly coupled coil is zero. D. The coefficient of self-inductance is proportional to the square of number of turns on it. 3. Which of the following statements about inductance of a coil is true? A. Inductance is a characteristic of coil occurring only in case of A.C. B. Inductance appears only if the coil has an iron core. C. Inductance is only another expression for self-induced voltage. D. Inductance characterizes the magnetic properties of a coil which are significant for the value of self-induced voltage generated due to current change in the coil. 4. A collapsing field around a coil A. tends to oppose the decay of coil current B. helps the decay of coil current C. tends to aid current flow reversal D. does not affect the coil current flow 5. Energy stored in an inductance is given by A. 2LI 2 joules B. 0 joule Nφ C. joules D. joules I 6. Which of the following is a vector quantity? A. magnetic potential B. flux density C. magnetic field intensity D. relative permeability 7. A conductor of length L has current I passing through it, when it is placed parallel to a strong magnetic field. The force experienced by the conductor will be A. BLI B. zero C. B2LI D. BL2I 8. Whenever a conductor cuts magnetic flux, an emf is induced in that conductor. This statement is due to A. Joule’s law B. Coulomb’s law C. Faraday’s law D. Weber and Ewing’s theory 9. The left hand rule correlates A. self induction, mutual induction and direction of force on a conductor B. magnetic field, electric field and direction of force on a conductor C. current, induced emf and direction of force on a conductor D. current, magnetic field and direction of force on a conductor 10. In the left hand rule, thumb always represents A. voltage B. current C. direction of force on conductor D. magnetic field A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 8 of 94  ELECTROMAGNETIC INDUCTION 11. The coefficient of coupling between two air core coils depends on A. self inductance of the two coils only B. mutual inductance between the two coils only C. mutual inductance and self inductance of the two coils D. none of the above 12. While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electric circuit? A. e.m.f. B. current density C. conductivity D. current 13. While comparing magnetic and electric circuits, the point of dissimilarity exists while considering A. flux and current flow B. permeance and conductance C. m.m.f. and e.m.f. D. reluctance and resistance 14. The effect of the inductance of a coil on a constant direct current is that A. it strengthens the current B. it does not affect the constant direct current C. it decreases the current D. it causes a higher voltage drop 15. Good smoothing factor of a coil depends on the A. terminal voltage B. property of the wire of the coil C. inductance of the coil D. cross-sectional area of the wire of the coil 16. Leakage factor is A. less than unity B. equal to unity C. more than unity D. zero 17. The law that induces emf and current always opposes the cause producing them was discovered by A. Lenz B. Faraday C. Maxwell D. Ohm 18. According to Lenz’s law the direction of induced e.m.f. and hence current A. may be found by the right hand rule B. always opposes the cause producing it C. is determined by the rate of cutting flux D. may be found by the left hand rule 19. Sparking occurs when a load is switched off because the circuit has high A. capacitance B. inductance C. resistance D. impedance d 20. The flux linked with a coil of inductance L carrying current i is (Li ) dt A. True B. False C. Partly true D. Partly false 21. When steel toroidal ring is magnetized by passing current through its coil, it develops no magnetic poles A. True B. False C. Partly true D. Partly false A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 9 of 94  ELECTROMAGNETIC INDUCTION 22. Air gap in the iron core of an inductor prevents A. hysteresis loss B. flux change C. transformer action D. core saturation 23. The growth of current in an inductive circuit follows A. hyperbolic law B. Ohm’s law C. exponential law D. linear law 24. The time constant of an inductive circuit is defined as the ratio of A. R/L B. Rt/L C. Lt/R D. L/R 25. The time constant is the time it takes the current in an inductive circuit to rise to A. 66% of its final steady state value B. 70% of its final steady state value C. 63% of its final steady state value D. 50% of its final steady state value 26. Mutual inductance can also be defined as: φ dt A. = B. M = N2 di di dt C. M = N2 D. M = N 2 dt dφ 27. The mutual inductance of two coils is maximum when the coils are A. inclined at an angle of 45 degrees B. at right angle to each other C. facing each other D. touching each other 28. The value of mutual inductance in terms of self inductance of the two coils L 1 and L2 is proportional to L1 A. L 1L 2 B. L2 C. L1 L 2 D. 29. Coupling coefficient k, a term much used in radio work can be obtained from A. K =M L1L 2 B. K = M L1 / L 2 C. = D. K = ML 1L 2 30. The coupling coefficient denotes A. the degree of magnetic linkage B. whether the reluctance remains constant C. the variation of inductance between the two coils D. whether the flux linkage is constant 31. It is difficult to magnetize steel because of its A. low permeability B. high retentivity C. high permeability D. high density A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 10 of 94  ELECTROMAGNETIC INDUCTION 32. In electrical machines, laminated cores are used with a view of reducing A. eddy current loss B. copper loss C. hysteresis loss D. windage loss 33. The area of hysteresis loop represents hysteresis loss in A. J/m3/s B. J/cycle C. J/s D. J/m3 34. According to Hysteresis law, hysteresis loss in a material is proportional to A. B1.2 B. B1.6 C. B0.6 D. B3.6 35. A degaussing is the process of A. removing gases from materials B. removal of magnetic impurities C. demagnetizing metallic part D. magnetizing nonmetallic part 36. Hysteresis losses can be reduced by A. using grain-oriented silicon steel B. increasing the frequency of the field C. laminating the core D. none of these A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 11 of 94  ELECTROSTATICS 1. Absolute permittivity of vacuum is taken as A. 8.854 x 10–6 farad/meter B. 8.854 x 10–12 farad/meter C. 8.854 x 10–9 farad/meter D. 8.854 x 1012 farad/meter 2. Relative permittivity of vacuum is A. zero B. 8.854 x 10–6 farad/meter C. unity D. 9 x 109 farad/meter 3. In the electric field, the potential is the work done in joules A. to bring positive charge of one coulomb from infinity to that point B. to bring any charge from infinity to that point C. in moving a unit positive charge from one point to the other point D. to bring any charge from any point to infinity 4. The unit of field intensity is A. coulomb B. coulomb/m2 C. newtons/coulomb D. newtons/m2 5. Coulomb’s law for the force between electric charges most closely resembles with A. Gauss theorem B. Newton’s law of gravitation C. Law of conservation of energy D. Newton’s laws of motion 6. Which of the following equations is correct? A. ∫Ed l = 0 B. ∫Ed s = q q C. ∫Ed s = D. ∫ l = ε0 → 7. The field F = yi + x j is a A. rotational field B. irrotational field C. conservative field D. static electric field 8. Dielectric strength of a material depends on A. moisture content B. thickness C. temperature D. all of these 9. What will happen to an insulating medium if voltage more than the breakdown voltage is applied? A. it will get punctured B. it will become magnetic C. it will melt D. its molecular structure will change 10. Which medium has the highest value of dielectric strength? A. glass B. mica C. porcelain D. quartz 11. The maximum value of potential gradient in a cable occurs in A. outer sheath B. insulation B. conductor D. uniformly all over A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 12 of 94  ELECTROSTATICS 12. A region around a stationary electric charge has A. electric field B. magnetic field C. both electric and magnetic field D. neither of the two 13. Inside a hollow spherical conductor A. electric field is constant B. electric field is zero C. electric field changes with distance from the center of the sphere D. electric field is unity 14. Capacitors are said to A. block a.c. and pass d.c. B. block d.c. and pass a.c. C. pass a.c. and d.c. D. block a.c. and d.c. 15. Which statement influences the capacity of a capacitor? A. area of the plates, thickness of the plates and the rate of charge B. area of the plates, dielectric and the rate of charge C. distance between the plates, dielectric and thickness of the plates D. distance between the plates, area of the plates and dielectric 16. The effect of the dielectric is to A. increase the capacitance B. decrease the capacitance C. reduce the working voltage D. increase the distance between the plates 17. Electrolytic capacitor is the most commonly used type but it has two disadvantages, namely A. low insulation resistance and suitable for d.c. only B. high insulation resistance and suitable for a.c. only C. high capacitance and high insulation resistance D. high capacitance and low insulation resistance 18. In a radio, a gang condenser is a type of A. air capacitor B. paper capacitor C. ceramic capacitor D. electrolytic capacitor 19. A sphere of one meter radius can attain a maximum potential of A. 1000 V B. 3 million volts C. 30 kV D. 3 kV 20. The power dissipated in a pure capacitor is A. maximum B. minimum C. zero D. depends on the size and voltage 21. One farad is A. coulomb–joule B. one coulomb per volt C. joule per volt D. one volt per coulomb 22. If a dielectric is placed in a electric field, the field strength A. decreases B. increases C. remains the same D. becomes zero A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 13 of 94  ELECTROSTATICS 23. If the medium of a parallel-plate capacitor consists of mica and air, the capacitance is increased by A. increasing the air space B. increasing the area of the plates C. decreasing the area of the plates D. increasing the thickness of mica 24. A capacitance C is charged through a resistance R. The time constant of the charging circuit is given by 1 C R A. RC B. C. D. RC R C 25. A circuit component that opposes the change in the circuit voltage is A. resistance B. inductance C. capacitance D. none of these 26. In a capacitor, the electric charge is stored in A. metal plates B. dielectric C. dielectric as well as metal plates D. neither dielectric nor metal plates 27. Internal heating of a capacitor is usually attributed to A. leakage resistance B. electron movement C. plate vibration D. dielectric charge 28. The ohmmeter reading for a shorted capacitor is A. infinity B. few kilo ohms C. few mega ohms D. zero A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 14 of 94  ELECTROLYSIS AND STORAGE BATTERIES 1. Electrochemical equivalent is A. ratio of atomic weight of an element to atomic weight of hydrogen B. mass of the element liberated per unit quantity of hydrogen C. ratio of atomic weight of valency D. none of the above 2. The mass of material deposited over an electrode is A. proportional to voltage B. proportional to time only C. proportional to current only D. proportional to quantity of electricity and electrochemical equivalent 3. The mass of an ion liberated at an electrode is directly proportional to the quantity of electricity which passes through the electrolyte. The above statement is associated with A. Gauss’s theorem B. Laplace law C. Weber and Ewing’s theory D. laws of electrolysis 4. In electroplating, the positive electrode is called the A. cathode B. anode C. terminal D. iontrap 5. Impurities in an electrolyte can cause an internal short circuit condition called A. depolarization B. electrolysis C. local action D. polarization 6. Distilled or approved water is used in electrolytes because it A. prevents or slows down local action B. speeds up electrochemical action C. improves specific gravity D. prevents polarization 7. The condition of a liquid electrolyte is measured in terms of its A. current value B. specific gravity C. acid content D. voltage output 8. One factor affecting voltages of the primary cell is the A. area of the plates B. distance between the plates C. types of plates and electrolyte D. thickness of the plates 9. Local action in the primary cell can be rectified by A. charging the cell B. amalgamating the zinc electrode with mercury C. using the cell for just few minutes D. dry cell 10. The action of a dry cell is to change A. chemical action to mechanical energy B. chemical action to electrical energy C. electrical energy into mechanical energy D. electrical energy into magnetic energy 11. Polarization in dry cell can be got rid of by A. coating the electrodes of the cell B. chemical means C. discharging the cell D. disposing the cell A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 15 of 94  ELECTROLYSIS AND STORAGE BATTERIES 12. The two main defects of the primary cell are A. polarization and sulphation B. local action and polarization C. buckling and polarization D. sulphation and buckling 13. The average dry cell gives an approximate voltage of A. 1.3 V B. 1.5 V C. 1.1 V D. 1.7 V 14. To obtain a high voltage of about 1.9 V from a dry cell, one would use A. Western standard cell B. Leclanche cell C. Nickel cadmium cell D. Magnesium cell 15. When n cells, each of emf E volts, and internal resistance r ohms are connected in series, the current i through an external resistance R ohms is given by E E A. i = B. i = r R +n R+ n E C. = D. i = + r + nR 16. When n cells, each of emf E volts, and internal resistance r ohms are connected in parallel, the strength of the current i is given by nE A. B. r +R + E E C. D. n + Rr n R+ r 17. Cells are connected in parallel to A. increase the internal resistance B. decrease the current capacity C. increase the current capacity D. increase the voltage output 18. Cells are connected in series to A. decrease the voltage output B. increase the voltage output C. decrease the internal resistance D. increase the current capacity 19. The function of the depolarizer in carbon zinc cell is that A. it converts the produced hydrogen into water B. it prevents the fast chemical action on the zinc container C. it synthesizes the decomposed electrolyte D. it absorbs the oxygen produced in the cell 20. Which of the following acts as depolarizer in dry cell? A. manganese dioxide B. zinc chloride C. ammonium chloride D. carbon powder 21. One advantage of a secondary cell is that it A. can be recharged B. can be used for portable equipment C. it is compact, easy to carry D. cannot be recharged A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 16 of 94  ELECTROLYSIS AND STORAGE BATTERIES 22. The composition of a secondary cell is A. zinc, copper and dilute sulphuric acid B. zinc, carbon and dilute sulphuric acid C. lead, lead peroxide and dilute sulphuric acid D. zinc, copper and dilute boric acid 23. Nickel-cadmium dry cell is becoming popular in power supplies to electronic calculators because A. it has a standard shape B. it is dry C. it is rechargeable D. it is easily manufactured 24. Secondary cell can produce large amounts of power for a A. short time and can be recharged B. long time and can be recharged C. short time and cannot be recharged D. long time and cannot be recharged 25. Gassing occurs in the process of A. charging an accumulator B. charging a dry cell C. discharging an accumulator D. discharging a dry cell 26. The condition of a secondary cell can be determined by A. its terminal voltage B. the color of the electrolyte C. the level of the electrolyte D. the terminal voltage and strength of the electrolyte 27. The lead acid accumulator should be recharged when the specific gravity of the electrolyte is about A. 1.15 B. 1.80 C. 1.25 D. 1.35 28. Other types of accumulators besides the lead acid type are A. alkaline batteries only B. alkaline and solar batteries C. alkaline and dry batteries D. nickel-cadmium batteries 29. Electrolyte of a storage battery is formed by adding A. water to hydrochloric acid B. sulphuric acid to water C. hydrochloric acid to water D. water to sulphuric acid 30. When the electrolyte of a storage battery is low it is usually proper to A. add a special weak acid solution B. top up with distilled water C. charge the battery for a short time before adding an electrolyte D. drain the battery completely and fill it with fresh electrolyte 31. The ampere hour capacity of battery depends on A. the thickness of the plates B. the area of the plates C. the strength of the electrolytes D. the distance between the plates 32. To keep the terminals of a lead acid storage battery free from corrosion, it is advisable to A. clean the terminals frequently B. charge for battery at frequent intervals C. keep the electrolyte level low D. apply petroleum jelly A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 17 of 94  ELECTROLYSIS AND STORAGE BATTERIES 33. The internal resistance of a discharged battery compared with a charged one A. is more B. is less C. remains the same D. is negative 34. It is not desirable to leave a lead storage battery in a discharged state for a long time mainly because A. electrolyte will attack the container B. plates will become sulphated C. electrolyte will become weak D. acid will evaporate 35. A partially discharged lead storage battery may be brought back to full charge by A. adding sulphuric acid B. adding distilled water C. applying ac voltage across the terminals D. applying dc voltage across the terminals 36. Which of the following is a primary cell A. mercury oxide B. lead-acid C. nickel-iron-alkaline D. nickel-cadmium-alkaline 37. Charging a lead-acid cell causes the electrolyte to become A. stronger B. stable C. weaker D. water 38. Separators in storage battery cell are designed to prevent the plates from A. touching the electrolyte B. touching the container C. shorting together D. shorting to the sediment 39. Which of the following affects the capacity of a lead-acid battery? A. temperature B. discharge time C. specific gravity D. all of these 40. During the charging period of a lead-acid battery, the charging rate is lowered to prevent violent gassing because A. the gasses given off are explosive B. evaporation of the electrolyte will weaken its effect C. the cells will be subjected to excessive pressure D. violent gassing tends to wash the active material from the plates 41. A fuel cell converts _______ energy into electrical energy. A. mechanical B. magnetic C. chemical D. solar 42. A cell which is used as voltage reference source for instrument calibration is A. solar cell B. dry cell C. mercury-cadmium cell D. nickel-cadmium cell 43. The advantage of the iron-nickel battery over the lead-acid battery is that A. it has a much higher efficiency B. it needs less maintenance C. the cell voltage of the iron-nickel battery is higher D. it is much cheaper 44. While charging accumulators, one should A. check the acid level with a lighted match B. short the cells to see if they are full charged C. keep them in a well-ventilated space D. connect and disconnect them with the supply on A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 18 of 94  D.C. GENERATORS 1. The output voltage of a single loop generator is a A. steady d.c. B. steady a.c. C. pulsating a.c. D. pulsating d.c. 2. A smooth output from a generator is obtained by A. design of the armature winding B. changing the form of the commutator C. changing the field strength D. design of the commutator 3. The output voltage of a generator is given by the equation di dφ A. E = V − I aR a B. = + C. E = −L D. E = N dt dt 4. What effect on current flow does reversing the direction of movement of a conductor in the magnetic field of a generator have A. neutralizes the current flow B. has no effect on current C. it reverses the direction of current flow D. has no effect on the voltage 5. 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 into mechanical energy D. converting chemical energy into electrical energy 6. How would you determine, from visual observation of the armature winding, whether a generator is lap or wave wound A. connection to the field winding B. connection to the commutator C. connection to the brushes D. the direction of the end connection 7. What classification is given to a d.c. generator that receives its field excitation current from internal source? A. self excited B. controlled excitation C. separately excited D. internally excited 8. 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 9. For all symbols having their usual meaning, the emf generated in the lap winding is given by φLN  P  φZNA A. E =   B. E = 60  2  2P   φZN  A  C. =   D. E =     120  P  A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 19 of 94  D.C. GENERATORS 10. Residual magnetism is necessary in a A. separately excited generator B. self excited generator C. both of these D. none of these 11. If the number of poles in a lap wounded generator is increased by a factor of 2, the generated emf will A. remain the same B. increase by a factor of 2 C. decrease by a factor of 2 D. increase by a factor of 4 12. Electric dc generators have normally, an overall efficiency of the order of A. 60-80% B. 75-85% C. 80-90% D. 85-95% 13. The armature magnetic field has effect that A. it demagnetizes or weakens the main flux B. it cross magnetizes, or distorts it C. it magnetizes or strengthens the main flux D. A and B 14. Brushes are always placed along A. magnetic neutral axis (MNA) B. geometric neutral axis (GNA) C. perpendicular to MNA D. perpendicular to GNA 15. Magnetic neutral axis makes an angle of _________ with the flux passing through the armature. A. 0o B. 90o C. 45o D. 180o 16. 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 17. If Өm is the forward lead angle in radians, Z is the total number of conductors and I is the current in each armature pole, the demagnetizing ampere-turns/pole are given as θ A. ATa = ZI × m B. = × 180  1 2θ  C. ATa = ZI − m  D. none of these  P 3π  18. The function of a compensating winding is to neutralize the A. reactance voltage generated as a consequence of commutation B. cross magnetize the effect of armature reaction C. demagnetizing effect of armature reaction D. all of these 19. In the commutation process it is the A. current which is getting reversed B. voltage which is getting reversed C. both of these D. none of these A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 20 of 94  D.C. GENERATORS 20. 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 is maximum C. flux linked with conductor is maximum D. flux linked with conductor is minimum 21. A simple method of increasing the voltage of a dc generator is A. to decrease the air gap flux density B. to increase the speed of rotation C. to decrease the speed of rotation D. to increase the length of the armature 22. 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 segments in the commutator C. to neutralize the reactance voltage by producing a reverse emf in the short circuit coil under commutation D. all of the above 23. The function of interpole or compole is A. to neutralize the reactance voltage and help in commutation process B. to neutralize the cross-magnetizing effect of armature reaction C. to neutralize the demagnetizing effect of the armature D. A and B 24. Interpoles are connected in _______ with the armature and compensating windings are connected in _______ with the armature. A. series, series B. series, shunt C. shunt, series D. shunt, shunt 25. The function of an equalizer ring is A. to avoid unequal distribution of current at the brushes B. to help to get sparkless commutation C. both of these D. none of these 26. Generators are often preferred to be run in parallel because of having the advantages of A. great reliability B. generator efficiency C. meeting greater load demand D. all of the above 27. 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 are equally suitable 28. Critical resistance of a dc generator R c A. Rc α (speed)–1 B. Rc α (speed) C. Rc α (speed)2 D. Rc α (speed)–2 29. 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 A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 21 of 94  D.C. GENERATORS 30. Equalizer connections are required when paralleling two A. compound generators B. series generators C. shunt generators C. long shunt generators 31. The function of an interpole is A. neutralize cross-field of armature reaction and obtain ideal commutation B. increase the armature reaction and thus obtain ideal commutation C. neutralize cross field of the armature reaction and thus obtain under commutation D. increase the armature reaction and thus obtain over commutation 32. Interpoles are normally connected in A. parallel with field B. series with the field C. parallel with the load D. series with the load 33. In DC generators, lap winding is used for A. low voltage, low current B. high voltage, high current C. low voltage, high current D. high voltage, low current 34. DC generators preferred for charging automobile batteries is A. shunt generator B. series generator C. long shunt compound generator D. short shunt generator 35. Which of the following component of a dc generator plays vital role for providing direct current of a dc generator? A. dummy coils B. equalizer rings C. eye bolt D. commutator 36. In dc generator the ripples in the direct emf and generated are reduced by A. using equalizer rings B. using commutator with large number of segments C. using carbon brushes of superior quality D. using carbon brushes of excellent quality 37. Which of the following generators are preferred for parallel operations? A. series generator B. shunt generator C. compound generator D. all of the above 38. Full load efficiency of the generator will be A. 68.5% B. 73.5% C. 80.8% D. 92.51% 39. Which loss in dc generator varies with load A. copper loss B. eddy current loss C. hysteresis loss D. windage loss 40. In dc generator, the cause of rapid brush wear may be A. imperfect contact B. sever sparking C. rough commutator surface D. any of the above 41. In a shunt generator, the voltage built up generally restricted by A. speed limitation B. armature heating C. saturation of iron D. brush wear A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 22 of 94  D.C. GENERATORS 42. 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 43. Which of the following helps in reducing the effect of armature reaction in dc generator? A. compensating windings B. interpoles C. both A and B D. neither A nor B 44. With dc generator, which of the following regulation is preferred A. 1% regulation B. 50% regulation C. infinite regulation D. 100% regulation A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 23 of 94  D.C. MOTORS 1. What is the effect produced by the electric motor? A. magnetic effect only B. magnetic as well as heating effect C. heating effect only D. heating as well as chemical effect 2. The rotating part of a dc motor is know as A. pole B. stator C. armature D. carbon brush 3. The function of the commutator in a dc machine is A. to change alternating current to direct current B. to improve commutation C. for easy speed control D. to change alternating voltage to direct voltage 4. Carbon brushes are used in electric motors to A. brush off carbon deposits on the commutator B. provide a path for flow of current C. prevent overheating of armature windings D. prevent sparking during commutation 5. Voltage equation for dc motor is A. V = Eb + IaRa B. V = Eb – IaRa C. Eb = V + IaRa D. Eb = V – IaRa 6. Condition for maximum power output for a dc motor is 1 A. Eb = V B. Eb = V/2 C. Eb = IaRa D. Eb = IaRa 2 7. 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 8. The highest speed attained by a dc shunt motor is A. equal to infinity of 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 9. In a dc motor iron losses occur in A. the yoke B. the armature C. the field D. none of these 10. The dummy coil in 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 A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 24 of 94  D.C. MOTORS 11. An external resistance is added in the 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 drawn by the motor D. to reduce the losses 12. The speed of a dc shunt motor is required to be more than F.L. speed. This is possible by A. increasing the armature B. decreasing the armature current C. increasing the excitation current D. reducing the field current 13. If speed of a dc shunt motor increases, the back emf A. increases B. decreases C. remains constant D. decreases and then increases 14. The current flowing in the conductors of a dc motor is A. ac B. dc C. ac as well as dc D. transients 15. As the load is increased the speed of a dc shunt motor will A. remain constant B. increase proportionately C. increase slightly D. reduce slightly 16. The current drawn by armature of a dc motor is V Eb − Eb − V A. B. C. D. Ra Ra Ra 17. If the current in the armature of a dc series motor is reduced to 5%, 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. 125% of the previous value 18. The shunt current flowing in short shunt compound-wound motor is given by V + I R A. I sh = B. = C. I sh = V − sc sc D. none of these R sh R sh 19. 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 and armature current remains the same C. speed will be half and armature current becomes double D. speed and armature current will remain the same 20. One dc motor drives another dc motor. The second dc motor when excited and driven A. runs B. does not run as a generator D. runs as a generator D. also runs as a motor A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 25 of 94  D.C. MOTORS 21. Armature torque of a dc motor is given by P P A. T = 0.159φZI a   kg-m B. T = 0.1620 / 2I a   N-m A A P C. = N-m D. T= kg-m A 22. The torque of a motor is A. the force in N-m acting on the rotor B. the product of tangential force on the rotor and its radius C. the electrical power in kW D. the power given to load being driven by the motor 23. The armature current drawn by any dc motor is proportional to A. the voltage applied to the motor B. the torque required C. the flux required in the motor D. the speed of the motor 24. The output power of any electrical motor is taken from A. the armature B. the coupling mounted on the shaft C. the conductors D. the poles 25. The power stated on the name plate of any motor is always A. the output power of the shaft B. the power drawn in kVA C. the power drawn in kW D. the gross power 26. A starter is necessary to start a dc motor because A. it starts the motor B. it limits the speed of the motor C. it limits the back emf to a safe value D. it limits the starting current to safe value 27. The efficiency of any electrical machine/apparatus will be high, if A. its losses are minimum B. its losses are more C. voltage applied is constant D. the current drawn is minimum 28. The direction of rotation of a dc motor is reversed by A. reversing armature connections B. interchanging the armature and field connection C. adding resistance to the field circuit D. reversing supply connection 29. The armature of dc motor is laminated A. to reduce the hysteresis losses B. to reduce the eddy current losses C. to reduce the inductivity of armature D. to reduce the mass of the armature 30. Which of the following is a correct statement about a series motor? A. its field winding consists of thicker wire and less turns B. it can run easily without a load C. it has an almost constant speed D. it has a poor torque A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 26 of 94  D.C. MOTORS 31. Which of the following dc motors has the least drop in speed between no load and nomi nal 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 32. The speed of a series motor at no load is A. zero B. 3000 rpm C. 3600 rpm D. infinity 33. The speed of dc series motor decreases if the flux in the field winding A. remains constant B. increases C. decreases D. none of these 34. Which of the following motors is used to derive the constant speed line shafting lathes, blowers and fans? A. DC shunt motor B. DC sreis motor C. cumulative compound motor D. differential compound motor 35. If the back emf in a dc motor is absent, then A. motor will run at very high speed B. motor will run at very low speed C. motor will not run at all D. motor will burn 36. The field flux of a dc motor can be controlled to achieve A. the speeds lower than rated speed B. the speeds higher than rated speed C. the speeds at rated speed D. none of these 37. 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 decreased D. none of these 38. DC series motors are best suited for traction work because A. torque is proportional to the square of armature current and speed is inversely proportional to torque. B. torque is proportional to the square of armature current and speed is proportional to torque. C. torque and speed is proportional to the square of armature current. D. none of these 39. A series motor is started without load. The effect is that A. the torque increases rapidly B. the speed increase rapidly C. the current drawn increases rapidly D. the back emf decreases 40. The direction of rotation of a dc series motor can be reversed by interchanging A. the supply terminals only B. the field terminals only C. the supply as well as field terminals D. none of these 41. The motor used for intermittent, high torque is A. dc shunt motor B. dc series motor C. differential compound motor D. cumulative compound motor A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 27 of 94  D.C. MOTORS 42. If the field of a dc shunt motor is opened 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 43. Which of the following motors is used for rolling mills? A. DC shunt motor B. DC cumulative compound motor C. DC series motor D. DC differential compound motor 44. Armature reaction is attributed to A. the effect of magnetic field set-up by the armature current B. the effect of magnetic field set-up by the field current C. copper loss in the armature D. the effect of magnetic field set-up by back emf 45. What will happen if the supply terminals of a 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 reverse D. Motor will run at a speed lower than the normal speed in the same direction 46. When the electric train is moving down a hill the dc motor acts as A. dc series motor B. dc shunt motor C. dc series generator D. dc shunt generator 47. Which of the following motors is suitable for high starting torque? A. shunt motor B. cumulative compound motor C. series motor D. compound motor 48. For which of the following dc motors is the typical field of application mentioned? A. shunt motor : electric trains B. series motor : machine tools C. series motor : belt drive D. compound motor : fly wheel drive 49. Why is the air gap between 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 50. Interpoles are meant for A. increasing the speed of the motor B. decreasing the counter emf C. reducing sparking at the commutator D. converting armature current to dc 51. Which of the following methods is most economical for finding the no-load losses of a large dc shunt motor is A. Hopkinson’s test B. Swinburne’s test C. retardation test D. none of these A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 28 of 94  D.C. MOTORS 52. The rated speed of a given dc shunt motor is 1050 rpm. To run this machine at 1200 rpm. Which of the following speed control scheme will be used? A. armature current resistance control B. field resistance control C. Ward-Leonard control D. none of these 53. 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 a starter to the motor C. it may develop excessive speed and damage itself D. none of these 54. 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. unity 55. A 230 V dc series motor is connected to 230 V ac. It will A. run slowly B. not run at all C. run with less efficiency D. run faster than its rated speed 56. The main function of a commutator in a dc motor is to A. prevent sparking B. convert ac to dc C. reduce friction D. convert dc to ac 57. 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 its full-load current B. will produce excessive line voltage drop C. will damage the commutator D. will produce very slow starting torque A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 29 of 94  A.C. FUNDAMENTALS 1. When using circuit laws and rules we must use A. maximum value B. effective value C. average value D. peak to peak value 2. A 60 Hz frequency would cause an electric light to A. turn on and off 120 times per second B. flicker noticeable C. turn on and off 180 times per second D. turn on and off 60 times per second 3. The relationship between frequency f, number of revolutions per second N and pair of poles P is given by A. f = n/p B. f = n/2p C. f = np D. f = 2np 4. The difference between peak +ve value and the peak –ve value of an a.c. voltage is called A. maximum value B. average value C. effective value D. peak to peak value 5. The greatest value attained during one half of the cycle is called A. peak value B. average value C. rms value D. effective value 6. The root mean square (r.m.s) value of an a.c. is the same as A. instantaneous value B. effective value C. average value D. maximum value 7. The rms value of a sine wave is equal to A. 0.637 max. value B. 0.707 max. value C. 0.506 max. value D. 1.414 max. value 8. Form factor is defined as A. rms value/peak value B. max. value/rms value C. rms value/average value D. effective value/rms value 9. The value of form factor for a pure sine wave is A. 1.414 B. 0.707 C. 0.637 D. 1.11 10. The value of peak factor for a pure sine wave is A. 1.414 B. 0.707 C. 0.637 D. 1.11 11. If the current and voltage are out of phase by 90 degrees, the power is A. 1.1 V.I. B. maximum C. minimum D. zero 12. If e1 = A sin ωt and e2 = B sin (ωt - Ө) then A. e1 lags e2 by Ө B. e2 lags e1 by Ө C. e2 leads e1 by Ө D. e1 leads e2 by Ө 13. Average value of a sine wave is 2 times the maximum value A. True B. False C. Partly true D. Partly false A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 30 of 94  A.C. FUNDAMENTALS 14. Which of the following frequencies has the longest period? A. 1 Hz B. 10 Hz C. 1 kHz D. 100 kHz 15. RMS value and the mean value is the same in case of A. square wave B. sine wave C. triangular scale D. half wave rectified sine wave 16. When the sole purpose of an alternating current is to produce heat, the selection of conductor is based on A. average value of current B. peak value of current C. rms value of current D. any of the above 17. The form factor of dc supply voltage is always A. infinite B. zero C. 0.5 D. unity 18. The period of the voltage 2 cos 4500πt + 7 sin 7500 πt is A. 2.51 s B. 2.51 ns C. 2.51 ms D. 2.51µs A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 31 of 94  A.C. CIRCUITS (SERIES AND PARALLEL) 1. The total voltage in a series RL circuit ______ the current by an angle _____. A. lags, of 90o B. lags, between 0o and 90o C. leads, between 0o and 90o D. leads, between 90o and 180o 2. In a series RL circuit, the inductor current _____ the resistor current. A. lags B. leads C. is equal D. is negative 3. The impedance triangle is similar to the _______ triangle with the resistance phasor in place of the ________. A. current, resistor current B. current, resistor voltage C. voltage, impedance D. voltage, resistor voltage 4. In the impedance triangle, the inductive reactance and impedance phasor are analogous to the ________ and ________ phasor respectively in the voltage triangle. A. inductive voltage, total voltage B. inductive current, total current C. inductive voltage, resistive voltage D. inductive current, resistive current 5. In a series RL circuit phasor diagram, total voltage may be presented by the ________ phasor and the resistor voltage may be represented by the ________ phasor. A. current, voltage B. current resistance, current C. impedance, resistance D. impedance, inductance 6. The phase angle of a series RL circuit is the angle between the ________ phasor and the ________ phasor. A. resistance, inductive reactance B. resistance, impedance C. inductive reactance, impedance D. inductance, impedance 7. The phase angle of a series RL circuit may be computed ______ as _______ or _______ or _______. A. cos–1 R/XL, sin–1 XL/R, tan–1 R/Z B. cos–1 R/Z, sin–1 XL/R, tan–1 R/XL C. cos–1 Z/XL, sin–1 R/Z, tan–1 XL/R D. cos–1 R/Z, sin–1 XL/Z, tan–1 XL/R 8. A(n) _______ stores and returns energy to a circuit while a(n) _________ dissipates energy. A. resistor, impedance B. resistor, inductor C. inductor, resistor D. inductor, reactance 9. For an RL circuit, the power factor cannot be less than _________ or greater than _________. A. 0, 1 B. 1, 0 C. 0, –1 D. –1, 0 10. The voltage across a capacitor _________ the current thought it by ____ ____. A. lags, 45o B. lags, 90o C. leads, 0o D. leads, 90o 11. If the resistance in a series RC circuit is increased the magnitude of the phase angle A. increases B. remains the same C. decreases D. changes in an indeterminate manner 12. In a series RC circuit, the current _______ the total voltage by an angle _______. A. lags, of 45o B. lags, of 0o o o C. leads, between 0 and 90 D. leads, of 90o A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 32 of 94  A.C. CIRCUITS (SERIES AND PARALLEL) 13. The resistance phasor for a series RC circuit points out to the right. The capacitive reactance phasor points _________ while the diagonal of the rectangle having there two phasors as sides represents the____________. A. up, impedance B. down, impedance C. left, current D. up, total voltage 14. The phase angle for a series RC circuit is defined as the angle between the ______ and the ________ phasors A. current, resistance voltage B. current, total voltage C. resistance voltage, capacitor voltage D. R, XC 15. The phase angle for a series RC circuit may be computed as the angle between the ______ and _______ phasors A. resistance, impedance B. resistance, reactance C. resistance, capacitance D. impedance, reactance 16. The net reactance in a n RLC circuit is A. XL B. XC C. XC – XL D. XL – XC 17. The impedance of a series RLC circuit is 2 2 2 2 A. R 2 + XL + X C B. R 2 + XL − X C C. R 2 + (X L + X C ) 2 D. + − 18. There will ________ be a frequency, called the _________ frequency at which ___________. A. sometimes, natural; XL = XC B. always, natural; R = 0 C. always, resonant; XL = XC D. sometimes, resonant; R = 0 19. The formula for the resonant frequency is f = A. LC B. 1 LC C. 2π LC D. 20. For a series RLC circuit at resonance the current amplitude is ______ and for a fixed voltage amplitude and the power factor is _________ A. minimum, zero B. minimum, unity C. maximum, zero D. maximum, unity 21. In an RLC circuit, the impedance at resonance is A. maximum, B. minimum C. infinity D. zero 22. The current in RLC series circuit, i.e. at resonance is A. maximum B. minimum C. infinity D. zero 23. In RLC circuits, the current at resonance is A. maximum in series circuit and minimum in parallel circuit B. maximum in parallel circuit and minimum in series circuit C. maximum in both the circuits D. minimum in both the circuits A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 33 of 94  A.C. CIRCUITS (SERIES AND PARALLEL) 24. A series resonant circuit is capacitive at f = 100 Hz. The circuit will be inductive somewhere at A. f < 100 Hz B. f > 100 Hz C. f = 100 Hz by increasing the value of the resistance D. f = 0 25. At a frequency lass than the resonant frequency A. series circuit is capacitive and parallel circuit is inductive B. series circuit is inductive and parallel circuit is capacitive C. both circuits are inductive D. both circuits are capacitive 26. In series as well as parallel resonant circuits, increasing the value of resistance would lead to A. increase in the bandwidth of both the circuits B. decrease in the bandwidth of both the circuits C. increase in bandwidth in series circuit and decrease in parallel circuit D. decrease in bandwidth in series circuit and increase in parallel circuit 27. The value of current at resonance in a series RLC circuit is affected by the value of A. R B. C C. L D. all of these 28. In resonant circuits, the power factor at resonance is A. zero B. 1 C. 0.5 D. 0.707 29. Which of the following statements is true for a series RLC circuit tuned at resonant frequency? A. the voltage across C > applied voltage B. the voltage across L > applied voltage C. the voltage across L and C > the applied voltage D. the voltage across both L and C < the applied voltage 30. The frequency at which maximum voltage occurs across the inductance in RLC series circuit is 1 1 1 A. B. C. D. 2π LC 2π LC − R 2 LC − C 2 R 2 − 2π 2 31. The frequency at which maximum voltage occurs across the capacitance in RLC series circuit is 1 1 R2 1 1 R2 A. B. − C. D. − 2π LC 2π LC 2L2 2π LC 2 2L 32. If f1 and f2 are half power frequencies and f 0 be resonance frequency, the selectivity of RLC series circuit is given by f2 − f0 f 2 − f1 − f − f1 A. B. C. D. 2 f1 − f 0 f0 − 2f0 33. In a series RC circuit, the voltage across the capacitor and the resistor are 60 V and 80 V respectively. The input voltage should be A. 70∠45o V B. 100 –37o V C. 105∠–42o V D. 108∠–60o V A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 34 of 94  A.C. CIRCUITS (SERIES AND PARALLEL) 34. To a series RLC circuit, a voltage of 10 V is applied. If Q of the coil at resonant frequency is 20, the voltage across the inductor at resonant frequency will be A. 200 V B. 100 V C. 75 V D. 50 V 35. The currents flowing in L and C at parallel resonance are A. zero B. equal C. infinite D. different 36. The exact natural frequency of free oscillations in an oscillatory circuit with capacitance of 0.055 µF, inductance 2µH and resistance 1 ohm will be A. 478 kHz B. 337 kHz C. 272 kHz D. 192 kHz 37. A coil with large distributed capacitance has a A. low resistance B. low Q C. low resonant frequency D. high resonant frequency 38. The transient currents are due to A. voltage applied to circuit B. resistance of the circuit B. impedance of the circuit D. changes in stored energy in inductance and capacitance 39. To a highly inductive circuit, a small capacitance is added in series. The angle between voltage and current will A. increase B. decrease C. remain nearly the same D. become indeterminate A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 35 of 94  3-PHASE SYSTEM 1. In a balanced three phase star connected circuit the line voltages are equal A. to the line current B. to the phase voltage C. and so are the line currents D. but the line currents are unequal 2. The type of a.c. distribution system commonly used to supply both light and power is the A. open delta system B. three phase delta system C. three phase star system with neutral wire D. three phase star system without neutral wire 3. The phase displacement between phasors in polyphase system is always A. 90 degrees B. 30 degrees C. 120 degrees D. 360 degrees divided by the number of phases 4. In a balanced three phase star connected system the line voltage is 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 5. In a star connected system line current is A. 0.707 times the phase voltage B. 1.735 times the phase voltage C. equal to the phase current D. 1.414 times the phase voltage 6. The advantages of star connections over delta connections for some phase voltage is that it gives A. step down current B. extra step up voltage C. extra step up current D. extra step up power 7. Power in a three phase star system is equal to A. 3 × VL × I L × power factor B. 3 × Vph × I L × power factor C. 3 × VL × I ph × power factor D. × × × power factor 8. Power in a three phase delta system with balanced load is equal to A. 3 × VL × I L × power factor B. 3 × Vph × I ph × power factor C. 3 × Vph × I L × power factor D. 3 × VL × I L × power factor 9. In a delta connected system the line current is 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 10. Power in star connected system is A. equal to that of delta system B. 2 times that of delta system C. 3 times that of delta system D. 3 times that of delta system A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 36 of 94  3-PHASE SYSTEM 11. For an unbalanced load which connection is suitable A. 3 wire open delta B. 4 wire star connection C. 3 wire delta connection D. 3 wire star connection 12. What is the minimum number of wattmeters required for measuring power of a three phase balanced load? A. two B. four C. one D. three 13. The power is to be measured for a balanced delta connected load whose terminals cannot be opened. How many wattmeters do you need? A. four B. one C. two D. three 14. What is the minimum number of wattmeters required to measure unbalanced power for a three phase system? A. two B. four C. three D. one 15. In two wattmeter method, the readings of the wattmeter will be identical when A. load in one of the phases is zero B. power factor is unity C. power factor is 0.5 D. neutral is earthed 16. Two wattmeters can be used to measure 3-phase power for a A. balanced and unbalanced load B. unbalanced load only C. balanced load only D. unity power factor only 17. In two wattmeter method, the reading of one of the wattmeter will be zero when A. power factor is unity B. power factor is 0.5 C. load in one of the phases is zero D. a neutral wire is not provided 18. For a three phase unbalanced load A. the power factor of each phase will be in proportional to the load B. the power factor of each phase will be the same C. the power factor of at least one of the phase must be leading D. the power factor of each phase may be different A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 37 of 94  POWER FACTOR 1. In a pure reactive circuit, the power factor is A. lagging B. zero C. leading D. unity 2. Power factor is defines as the ratio of A. volt amperes to watts B. watts to volt amperes C. volt amperes reactive to watts D. watts to volt amperes reactive 3. In a series circuit consisting of resistance and reactance, power factor is defined as the ratio of A. resistance to impedance B. resistance to reactance C. reactance to impedance D. reactance to resistance 4. For a parallel circuit consisting of resistance and reactance, the value of power factor is the ratio of A. impedance to reactance B. reactance to impedance C. resistance to impedance D. impedance to resistance 5. It is not easy to find the value of impedance for a parallel circuit but power factor can easily be obtained as a ratio of A. active current to line current B. reactive current to line current C. line current to active current D. line current to reactive current 6. The power factor of a.c. circuit containing both a resistor and a conductor is A. more than unity B. leading by 90 degrees C. between 0 – 1 leading D. between 0 – 1 lagging 7. In an a.c. circuit, a low value of reactive volt ampere compared with watts indicates A. high power factor B. unity power factor C. leading power factor D. low power factor 8. In a given circuit when power factor is unity the reactive power is A. a maximum B. equal to I2R C. zero D. a minimum 9. The capacitor of power factor correction are rated in terms of A. voltage B. VA C. kW D. kVAR 10. Poor power factor results in all of the following except A. overloading of transformers B. overloading of alternators C. reduction in power losses D. reduction in load handling capacity of electrical system 11. Power factor of an inductive circuit can be improved by connecting a capacitor to it in A. series B. parallel C. either series or parallel D. depends on the value of the capacitor 12. For the same load, if the power factor of load is reduced, it will A. draw more current B. less current C. same current but less power D. less current but more power 13. The power factor of incandescent bulb is A. 0.8 lagging B. 0.8 leading C. unity D. zero A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 38 of 94  POWER FACTOR 14. Power factor of magnetizing component of a transformer is A. unity B. 0.8 leading C. always leading D. zero 15. One of the reasons for improving the power factor is A. to increase the reactive power B. to decrease the reactive power C. to increase the real power D. none of these 16. Another reason for improving the power factor is A. to avoid poor voltage regulation B. to keep voltage regulation constant C. to increase the voltage regulation D. to decrease the voltage regulation 17. Power factor improvement may be achieved by the use of A. synchronous motor B. induction motor C. long transmission line D. short transmission line 18. The advantage of using static capacitor to improve the power factor is because they A. are not variable B. are almost loss free C. provide continuous change of power factor D. all of the above 19. Many industrial tariffs penalize consumers whose power factor falls A. below 0.8 B. below unity C. between 0.8 to 0.95 D. between 0.95 to unity 19. A factory takes a load of 1000 KW and has a reactive power of 1000 KVA. Its power factor is A. 0.6 B. unity C. 0.8 D. 0.7 20. A current of 10 amperes at a power factor of 0.8 lagging is taken from 250 V a.c. supply. The reactive power of the system is A. 2000 watts B. 2000 VA C. 1500 watts D. 1500 Var A_Compilation_of_Objective_Type_Questions_in_Electrical_Engineering 39 of 94  NETWORK THEOREMS 1. Kirchhoff’s voltage law is not valid for a non-linear network. A. True B. False C. Partly true D. Partly False 2. Kirchhoff's law is applicable to A. AC circuits only B. passive networks only C. AC as well as DC circuits D. DC circuits only 3. An ideal current source has zero A. voltage on no load B. internal resistance C. internal conductance D. current 4. A closed path made of several branches of the network is known as A. loop B. junction C. branch D. division 5. An ideal voltage source is that which A. has terminal voltage in proportion to current B. has zero internal r