Basic Electrical Engineering 1st Year 2024 Past Paper PDF

Basic Electrical Engineering Department of Electrical Engineering, BCET Suggestion for 1 Marks questions Refer to HoD, EE (Accepted after 3rd modification) Provide to AIML department (1st year, 2024) 1. What is fuse? 2. What is the efficiency of power t...

Basic Electrical Engineering Department of Electrical Engineering, BCET Suggestion for 1 Marks questions Refer to HoD, EE (Accepted after 3rd modification) Provide to AIML department (1st year, 2024) 1. What is fuse? 2. What is the efficiency of power transfer when maximum transfer of power occurs? 3. In a series RLC circuit, what is the condition for resonance? 4. What is Core type Transformer? 5. What is basic principle of operation of alternators/Dc generators? 6. What is duty cycle? 7. What is the function of a transformer? 8. What is synchronous speed? 9. What is the main classification of inverter? 10. What is secondary cell? 11. What will be the impedance of a coil contains resistance of 8.0 ohm and inductive reactance of 6 ohm? 12. The full load copper loss of a transformer is 1600 W. At half load, what will be the copper loss? 13. What is the significance of form factor in AC Circuit? 14. What is shell type transformer? 15. What is Regulation of Transformer? 16. What is efficiency of the transformer? 17. Why iron losses are considered as constant loss and copper losses are considered as variable losses? 18. What is half power frequency? 19. What amount of average active power deliver by a pure resistor, Pure Inductor and Pure Capacitor? 20. Write down the emf equation of a single phase transformer. 21. What is the bandwidth of a series RLC circuit at resonance is______? 22. Transformer core is laminated to reduce ____? 23. Power factor for AC resistive circuit is ____? 24. For RLC series resonance circuit, line current at resonance frequency is maximum or minimum? 25. Two impedances (10+j10) and (10-j10) ohm are connected in parallel. Their equivalent Impedence is? 26. The direction of rotation of a DC motor is given by which law? 27. One commercial unit of electricity equals? 28. If a DC-DC buck converter of input voltage has chopping frequency of “f” and Ton as the on time of the switch, then the output voltage is? 29. The insulation resistance of earth of an installation should be nearly? This pdf contents 9 number of pdf, AIML Dept (From EE dept, BCET) Page 1  30. Form factor is the ratio of? 31. A device that converts a DC source into AC is called? 32. How many types of powers are there? Show them in Power triangle? 33. What is a Converter? 34. What is the Inverter? 35. Can we operate transformer in DC? 36. The form factor of a current waveform is 1.The shape of the waveform is ? 37. The DC motor needs a starter during starting to control? 38. The superposition theorem satisfies the principle of? 39. What is the relation between the input and output voltage of a Buck converter and Boost converter? 40. Two alternating currents are represented by L1 = sin(wt – 30) and L2=sin (wt +30). Which lags who by what angle? 41. What is the condition when maximum efficiency of the transformer occurs? 42. The frequency of emf induced in the rotor of 3 phase, 50 Hz induction motor at standstill is? 43. The field of a synchronous generator is excited by? 44. In a parallel AC circuit, if the supply frequency is greater than the resonant frequency, then the circuit is? 45. Thevenin theorem cannot be applied to______ networks (Option – (a) Liner (b) Non linear) 46. Area of hysteresis loop is a measure of? 47. The power factor of a purely resistive circuit is? 48. What is meant by the term “resistance” in an AC circuit? 49. The phase relationship between the primary and Secondary voltages of a transformer is? 50. At start , the slip of the induction motor is? 51. The expression for total power output of a delta connected system in terms of phase voltage and current is given by? 52. An open circuit may be considered as a resistor of value? 53. In a series RL circuit, the phase difference between the applied AC voltage and Current increases when? 54. Inductive reactance of a coil of inductance of 0.2 H at 50 Hz is ? 55. Iron losses in a DC machine are independent of variation in? 56. A series motor will run at very high speed when? 57. Three resistances of 4 ohm, 6 ohm and 8 ohm are connected in parallel. The maximum power dissipated will occur in? 58. The output of a DC generator is ____ wave? 59. In a transformer, the flux phasor _____ (Option - leads/lags) the induced emf by ___ degree. 60. When a 50 Hz transformer is operated at 400 Hz, its KVA rating is – 61. Power developed by DC motor is maximum when the ratio of back emf and applied voltage is? 62. The critical resistance of a DC generator refers to the resistance of? This pdf contents 9 number of pdf, AIML Dept (From EE dept, BCET) Page 2  63. A sinusoidal voltage is represented by v=141.4 sin (314.18 t – 90). The RMS value of the voltage, its frequency and phase angle are respectively? 64. A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full-load. The motor is wounded for _ poles. 65. In three-phase induction motor a) 3-phase supply is to be given to the stator winding and d.c. supply the rotor winding b) only 3-phase supply is to be given to the stator winding c) 3-phase supply is to be given to both stator and rotor winding d) 3-phase supply is to be given to rotor winding. 66. The slip of 400 V, 3-phase, 4-pole induction motor when rotating at 1440 rpm is _%. 67. The direction of current in an a.c. circuit is ___ (option – (a) varying (b) fixed) with time. 68. In a three-phase star connected system, the relation between the phase and the line voltage is? 69. When a pure inductance is connected to an a.c. source, the voltage.................... the current through it by..................... 70. The power consumed by a pure capacitance connected to a.c. source is___ 71. In a series RL circuit the phase difference between the applied a.c. voltage and current increases when a) R is increased b) X L is increased c) X L is decreased d) supply frequency is increased. 72. When a phasor is multiplied by j and – j, it is rotated through.................... in the anticlockwise direction respectively by a) 90°, 270° b) 90°, 90° c) 90°, 180° d) 270°, 90°. 73. An a.c. voltage of (100 + j 60 ) V is applied to a circuit to give a current of ( – 4 + j 10 ) A. The power dissipated by the current is a) – 100 W b) 100 W c) 200 W d) 400 W. 74. In a parallel a.c. circuit, if the supply frequency is greater than the resonant frequency, then the circuit is a) inductive b) resistive c) capacitive d) none of these. 75. Q factor of a series circuit consisting R = 10 ohms, L = 0·1 H and C = 10 µF is a) 115 b) 100 c) 10 d) 1. 76. If a parallel circuit is shunted by a resistance then the a) Q factor is increased b) impedance is decreased c) both (a) & (b) d) none of these. 77. Energy stored in a capacitor is given by____? 78. If an electrical circuit, if the current lags the voltage by 60 0, the circuit nature will be? (RC/RL/LC/None) 79. KVL is used for ____ analysis. 80. If E1=Asinwt and E2 = Asin (wt-P) then E1 ____ (option – Lead or lag) E2. 81. Iron loss of a transformer is 100 watt at half load. At full load the iron loss would be____? 82. What resistance R0 of the exciting branch of the equivalent circuit of a 3 phase induction motor represents? 83. A 3 phase 4 wire balanced system, the current of each phase is 10 A. The current through the neutral wire will be? 84. Inductive reactance of a coil of inductance 0.2 H at 50 Hz is a) 62.8 ohms b) 628 ohms c) 0.2 ohm d) 20 ohms. 85. In a 3 phase system, the emfs are a) 30˚ apart b) 60˚ apart c) 90˚ apart d) 120˚ apart. This pdf contents 9 number of pdf, AIML Dept (From EE dept, BCET) Page 3  86. The commutator of a D.C. machine acts as a a) full-wave rectifier b) half-wave rectifier c) controlled full-wave rectifier d) none of these. 87. Hysteresis loss in a transformer can be reduced by using a) Laminated Core b) Silicon Steel Core c) Oil d) None of these. 88. The three-phase slip-ring induction motor has a) short-circuited rotor b) double cage rotor c) wound rotor d) none of these. 89. The direction of rotation of a D.C. shunt motor can be reversed by interchanging its a) supply terminals b) shunt-field resistance c) shunt and armature terminals together d) none of these. 90. Value of absolute permittivity (ε) of air is ___? 91. The form factor of a sinusoidal wave is always equals to ___? 92. A three-phase 4-wire system supplies a balance star load. The current in each phase is 5A. The current in neutral will be a) 5√3A b) 0A c) 15 A d) 5A. 93. Superposition Theorem can be applied only to …………………….. Network. a) Linear b) Non-linear 94. The principle of operation of a transformer is based upon a) Self-induction b) Static induction c) Dynamic induction d) Mutual induction. 95. A 4-pole D.C generator is running at 1500rpm. The frequency of induced current in the armature is a) 25Hz b) 50Hz c) 100Hz d) zero. 96. A P pole lap wound D.C. machine has an armature current l A. The conductor current in the armature winding is a) l A b) P l A c) l A/P d) none of these. 97. An air gap is usually inserted in a magnetic circuit to a) Prevent saturation b) Increase the flux c) Increase the MMF d) Decrease the flux. (out of syllabus) 98. The output power is maximum for a D.C Motor when a) Eb = V/2 b) Eb = 0.5 laRa c) Eb = V d) Eb = laRa 99. The conductance G of a series R-L circuit having a resistance R and inductive reactance XL is given by a) G = 1 /R b) G = R /XL c) G = R /R 2 + XL 2 d) G = R2 /R2 + XL2. 100. Area of hysteresis loop is a measure of a) retentivity b) coercivity c) saturated flux density d) energy loss. 101. The power factor of a purely inductive circuit is a) zero b) one c) infinity d) 0·5. 102. Superposition theorem is not valid for a) voltage responses b) current responses c) power responses d) linear networks. 103. Total instantaneous power supplied by a 3-phase ac supply to a balanced R-L load is ____? 104. In an RL series circuit VL........VR , by............degrees. a) lags, 45 b) lags, 90 c) leads, 90 d) leads, 45. 105. The rms value of a sinusoidal ac current is equal to its value at a) 60 degree b) 45 degree c) 30 degree d) 90 degree. 106. An ideal current source has a) no resistance b) very high resistance in series c) infinite resistance in parallel d) low resistance in parallel. This pdf contents 9 number of pdf, AIML Dept (From EE dept, BCET) Page 4  107. The excitation current of a transformer is of the order of a) 2% of full load current b) 10% of full load current c) 50% of full load current d) 75% of full load current. 108. In series R-L-C circuit, the power factor at resonance is a) unity b) zero c) 0·5 d) 0·75. 109. In a transformer, electric power is transformed from one circuit to another without change in a) voltage b) current c) frequency d) turns. 110. The efficiency of a transformer is maximum when a) copper losses are zero b) iron losses are zero c) copper losses are 50% of the iron losses d) copper losses are equal to iron losses. 111.. v) The direction of emf generated in a dc generator can be determined from a) Lenz's law b) Kirchhoff's law c) Fleming's left hand rule d) Fleming's right hand. 112.. vi) The reluctance of a magnetic circuit depends on its a) length b) cross- sectional area and length c) resistivity d) cross-sectional 113. The core of a dc machine is laminated to reduce a) copper loss b) eddy current loss c) hysteresis loss d) thermal loss. 114. If e 1 = A sin wt and e 2 = B sin ( wt – φ ), then a) e 1 lags e 2 by φ b) e 2 lags e 1 by φ c) e 2 leads e 1 by φ d) e 1 is in phase with e 2. 115. In three-phase induction motor a) 3-phase supply is to be given to the stator winding & dc supply to the rotor winding b) only 3-phase supply is to be given to the stator winding c) 3-phase supply is to be given to both stator and rotor winding d) 3- phase supply is to be given to rotor winding 116. Three resistors of 4 Ω, 6 Ω, and 8 Ω are connected in parallel. In which resistor power dissipation is maximum? a) 4 Ω b) 6 Ω c) 8 Ω d) equal in all resistors. 117. In a 3-phase system, the phase voltages are a) 30° apart b) 60° apart c) 90° apart d) 120° apart 118. For a coil with N-turns the self-inductance will be proportional to a) N b) 1/N c) N d) 1/N2. 2 119. What do you understand by the terms electric potential and electric potential difference? 120. In an a.c. circuit having R, L & C in series & operating on lagging pf, increase in frequency will a) reduce the current b) increase the current c) both (a) and (b) are possible d) have no effect on current drawn 121. KCL is consequences of law of conservation of a) energy b) change c) flux d) all of these. 122. In a transformer, the resistance between the primary & secondary must be a) zero b) 1 kΩ c) 100 kΩ d) infinite. 123. The armature of a D.C. machine is laminated a) to reduce the hysteresis losses b) to reduce the eddy current losses c) to reduce the inductance of the armature d) to reduce the mass of the armature. 124. What will happen if the supply terminals of D.C. shunt motor are interchanged? a) Motor will stop b) The motor will run in the same original direction c) The direction of rotation will reverse d) Motor will run at a speed lower than the normal speed in the same direction. This pdf contents 9 number of pdf, AIML Dept (From EE dept, BCET) Page 5  125. The speed at which the rotating magnetic field produced by stator currents rotates is a) synchronous speed b) rotor speed c) greater than synchronous speed d) lower than synchronous speed. 126. A series circuit is given by z = 5 – J12. Its susceptance is a) 5/13 b) 5/169 c) 12/13 d) 12/169. 127. The D.C. motor needs a starter during starting to control a) speed b) current c) voltage d) flux. 128. The force experienced by a small conductor of length l, carrying current I, placed in a magnetic field ∅ B at an angle θ with respect to ∅ B is given by a) BIl b) BIl sin θ c) BIl cos θ d) zero. 129. If a D.C. series motor is started on no-load, its speed will be a) normal b) zero c) infinite d) below normal. 130. What are the components of LT switchgear? 131. What is the meaning of LT in “LT Switchgear”? 132. What is fusing factor? 133. What is fuse? 134. What types of fuse existed in real life? 135. What are the difference between MCB and Fuse. 136. What is MCB? What is MCCB? 137. What is the principle of MCB? 138. What is the full form of RCCB? 139. What are the voltage grades? 140. What is earthing? Is earthing and Neutral is same? 141. What is earth resistance? How to measure it? 142. What is the difference between the Primary and Secondary cell in a battery? 143. What is the difference between the EMF and PD of a cell? 144. What is UPS? What it is used? 145. In an AC circuit a low value of KVAR compared with KW indicates ____ (high/Low) power factor. 146. The frequency of an alternating current is? 147. The unit of frequency is? 148. When an alternating current passes through an ohmic resistance which electrical power (Active/Reactive/Apparent) converted into heat? 149. In an AC circuit (sine wave) with R and L in series which lag what by which angle? 150. A current is set to be alternating when it changes in? 151. The power factor of an ordinary electric bulb is (Ans – slightly less than unity) 152. The power factor of practical inductor is (Ans – lagging) 153. Unit of reactive power is (Ans – VAR) 154. Unit of inductive reactance is (Ans – ohm) 155. The R.M.S. value of a sine wave is 100 A. Its peak value is? (Ans – 141 A) 156. A circuit with a resistor, inductor and capacitor in series is resonant of f o Hz. If the all the component of values is now doubled the new resonant frequency is? (Ans – f0/2) This pdf contents 9 number of pdf, AIML Dept (From EE dept, BCET) Page 6  157. A current is said to be direct current when its (Ans - Magnitude remains constant with time) 158. A small capacitance is added to a highly inductive circuit what will happen? (Ans – power factor will increase) 159. Pure inductive circuit consume 100% reactive power and 0% active power. (Ans - Takes power from the line during some part of the cycle and then returns back to it during other part of the cycle) 160. In a pure inductive circuit which lag what by which angle? (Ans - The current legs behind the voltage by 90 o 161. In a purely inductive circuit what is the value of actual power? (Ans – 0) 162. The inductance of a coil can be increased by? (Ans - Choosing core material having high permeability) 163. In a purely inductive circuit if the supply frequency is reduced to 1/2, the current will be? (Ans – Doubled) 164. In a pure capacitive circuit if the supply frequency is reduced to 1/2, the current will be? (Ans – Reduced by half) 165. A step-up transformer increases........ (Ans – Voltage) 166. A transformer transforms what? 167. A transformer has negative voltage regulation when its load power factor is? (Ans – leading) 168. The main purpose of performing open-circuit test on a transformer is to measure its? (Ans – Core loss) [out of syllabus question but still asked in semester] 169. No-load test on a transformer is carried out to determine? (Ans - Magnetising current and no-load loss) [out of syllabus question but still asked in semester] 170. Transformers are rated in KVA instead of KW because? (Ans - Total transformer loss depends on volt-ampere) 171. Relatively light loads, transformer efficiency are low because? (Ans - Fixed loss is high in proportion to the output) 172. The all-day efficiency of a transformer depends primarily on? (Ans - Both (b) and (c)) 173. The no-load current drawn by transformer is usually – (Ans – 2 to 5 %) 174. Sumpner's test is conducted on transformers to determine? (Ans – Temperature) [out of syllabus question but still asked in semester) 175. Efficiency of a power transformer is of the order of? (Ans – 95% to 98%) 176. Transformer breaths in when? (Ans - Load on it decreases) 177. The transformer ratings are usually expressed in (Ans – KVA) 178. What does not change in an ordinary transformer? (Ans – frequency) 179. Star/star transformers work satisfactorily when? (Ans - Load is balanced only) 180. Delta/star transformer works satisfactorily when (Ans - On balanced as well as unbalanced loads) 181. An instrument which detects electric current is known as (Ans – Galvanometer) 182. Electric pressure is also called? (Ans – Voltage) 183. The S.I. unit of power is (Ans – Watt) This pdf contents 9 number of pdf, AIML Dept (From EE dept, BCET) Page 7  184. The filament of an electric bulb is made of? (Ans – tungsten) 185. The resistance of human body is around? (Ans – 1000 ohm) 186. What is resistance and conductance? What is active and passive element? 187. What is open and short circuit? 188. State KCL and KVL law? Which is remaining conservative in KCL and KVL? 189. Show current divider and voltage divider in any circuit. 190. State superposition, Thevenin and Norton theorem. 191. Draw a practical voltage and current source; convert it to ideal current source. What is the internal resistance of the ideal current source and ideal voltage source. 192. What do you mean by cycle, frequency, period, angular frequency of a sine waveform? 193. What is the power factor of (a) pure resistive load, (b) pure inductive load (c) pure capacitive load? 194. What is resonant frequency? What is Q factor? 195. Relation of current and voltage in star and delta connected three phase load. 196. What is neutral current in star connected system? 197. What is leakage flux? 198. What are the losses in transformer? 199. What is hysteresis loss? 200. What is eddy current loss? 201. What is the principle of transformer operation? 202. Write down the emf equation of a transformer? 203. What is voltage ratio and turn ratio of a transformer? 204. What is step up and step down transformer? 205. What is distribution transformer? What is power transformer? 206. What is the difference between the ideal and practical transformer? 207. Show equivalent circuit of a transformer. 208. What is voltage regulation of a transformer? Write down the formula for voltage regulation of a transformer? 209. What is the regulation in unity power factor? 210. What is the condition for the zero regulation? 211. What is the condition for maximum voltage regulation? 212. What is the difference between the hysteresis and eddy current loss? 213. What is the condition for the maximum efficiency? 214. What is auto transformer? 215. What is lap and wave winding? 216. What is commutation? 217. What is the principle of DC generator? 218. What is the relation between the speed and slip of a 3 phase induction motor. 219. Condition for maximum torque in a 3 phase induction motor. 220. Draw torque slip and torque speed characteristics of a 3 phase induction motors. 221. What do you mean by RMF? Why it is useful for machine to run? This pdf contents 9 number of pdf, AIML Dept (From EE dept, BCET) Page 8  222. What is the relation between the speed and frequency in synchronous generator (Alternator). 223. What is pitch factor? What is distribution factor? 224. What is damper winding? What it is very helpful for synchronous machine? 225. What is hunting? What is the effect of hunting? 226. What is the application of the synchronous machine, induction machines? 227. Is synchronous machine is self rotating? What techniques we use for the rotation of synchronous machines? 228. What is synchronous compensator? 229. What is buck chopper? What is buck chopper? Write down their formula of input and output voltages? What is use of a capacitor in a buck or boost converter? What is switch on and switch off condition for the chopper (buck and boost). 230. What is duty cycle? What is duty ratio control? What is cycloconverter? 231. What is PWM control? 232. What are an inverter and Rectifier? This pdf contents 9 number of pdf, AIML Dept (From EE dept, BCET) Page 9