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End of Semester Electrical Engineering Exam
Revision: 100 Multiple Choice Questions
- Ohm’s Law relates voltage (V), current (I), and resistance (R) as: a) V=I+RV = I + RV=I+R b) V=I/RV = I / RV=I/R c) V=I×RV = I \times RV=I×R d) V=R/IV = R / IV=R/I Answer: c
- The unit of electrical resistance is: a) Volt b) Ampere c) Ohm d) Watt Answer: c
- Kirchhoff’s Current Law (KCL) states that the algebraic sum of currents entering a node is: a) Equal to voltage at the node b) Zero c) Equal to resistance at the node d) Equal to power at the node Answer: b
- Kirchhoff’s Voltage Law (KVL) states that the algebraic sum of voltages around any closed loop is: a) Equal to current in the loop b) Equal to resistance in the loop c) Zero d) Equal to power in the loop Answer: c
- The power factor of a purely resistive circuit is: a) 0 b) 1 c) Less than 1
d) Greater than 1 Answer: b
- The function of a transformer is to: a) Convert AC to DC b) Change voltage levels c) Store electrical energy d) Control current flow Answer: b
- The RMS value of a sinusoidal voltage with peak value VmV_mVm is: a) VmV_mVm b) 2Vm2V_m2Vm c) Vm/2V_m / \sqrt{2}Vm/ d) Vm/2V_m / 2Vm/ Answer: c
- The unit of inductance is: a) Farad b) Ohm c) Henry d) Tesla Answer: c
- The unit of capacitance is: a) Henry b) Ohm c) Farad d) Tesla Answer: c 10.A diode allows current to flow: a) In both directions b) In one direction only c) Only when voltage is zero d) Only at high voltage Answer: b
c) Reactive power to real power d) Voltage to current Answer: b 17.The frequency of standard AC supply in most countries is: a) 25 Hz b) 50 Hz or 60 Hz c) 100 Hz d) 400 Hz Answer: b 18.The function of a fuse is to: a) Store energy b) Amplify signals c) Protect circuits from overcurrent d) Convert AC to DC Answer: c 19.The speed of a synchronous motor depends on: a) Load b) Supply frequency and number of poles c) Voltage d) Current Answer: b 20.The speed of an induction motor is: a) Equal to synchronous speed b) Less than synchronous speed c) Greater than synchronous speed d) Independent of synchronous speed Answer: b 21.The unit of electric charge is: a) Volt b) Ampere c) Coulomb d) Ohm Answer: c
22.The voltage induced in a coil due to change in magnetic flux is given by: a) Ohm’s law b) Faraday’s law c) Lenz’s law d) Kirchhoff’s law Answer: b 23.The direction of induced emf in a conductor is given by: a) Ohm’s law b) Kirchhoff’s law c) Lenz’s law d) Faraday’s law Answer: c 24.The unit of magnetic flux density is: a) Tesla b) Weber c) Tesla d) Henry Answer: c 25.The unit of magnetic flux is: a) Tesla b) Weber c) Henry d) Farad Answer: b 26.The function of a relay is to: a) Measure current b) Convert AC to DC c) Electrically operated switch d) Store energy Answer: c 27.The power consumed in a purely inductive AC circuit is: a) Zero b) Maximum
d) Ohm Answer: c 33.The unit of electrical energy is: a) Watt b) Volt c) Kilowatt-hour (kWh) d) Ampere Answer: c 34.The device used to convert AC to DC is called: a) Transformer b) Rectifier c) Inverter d) Rectifier Answer: d 35.The device used to convert DC to AC is called: a) Transformer b) Inverter c) Rectifier d) Converter Answer: b 36.The speed of a DC motor is controlled by: a) Voltage applied b) Field current c) Armature resistance d) All of the above Answer: d 37.The back emf in a DC motor opposes: a) Armature current b) Applied voltage c) Field flux d) Load torque Answer: b
38.The commutator in a DC motor is used to: a) Increase voltage b) Decrease current c) Reverse current direction in the armature d) Store energy Answer: c 39.The torque in a DC motor is proportional to: a) Armature voltage b) Armature current and field flux c) Speed d) Resistance Answer: b 40.The starting torque of a squirrel cage induction motor is: a) Zero b) Low c) High d) Infinite Answer: c 41.The slip of an induction motor at synchronous speed is: a) 1 b) 0. c) 0 d) Infinity Answer: c 42.The slip of an induction motor at standstill is: a) 0 b) 0. c) 1 d) Infinity Answer: c 43.The main loss in transformers includes: a) Copper loss b) Core loss
resistance Answer: d 49.Norton’s theorem states that any linear bilateral network can be replaced by: a) Voltage source and series resistance b) Current source and parallel resistance c) Voltage source and parallel resistance d) Current source and series resistance Answer: b 50.The superposition theorem applies to: a) Non-linear circuits b) Circuits with dependent sources c) Linear circuits with multiple independent sources d) Circuits with only one source Answer: c 51.The time constant of an RC circuit is: a) R×CR \times CR×C b) R/CR / CR/C c) R×CR \times CR×C d) 1/(R×C)1 / (R \times C)1/(R×C) Answer: c 52.The time constant of an RL circuit is: a) L/RL / RL/R b) R/LR / LR/L c) L/RL / RL/R d) R×LR \times LR×L Answer: c 53.The transient response of an RC circuit is characterized by: a) Exponential rise or decay b) Sinusoidal oscillations c) Exponential rise or decay d) Linear change Answer: c
54.The transient response of an RL circuit is characterized by: a) Exponential rise or decay b) Sinusoidal oscillations c) Exponential rise or decay d) Linear change Answer: c 55.The maximum torque in a synchronous motor occurs at: a) Zero load b) Full load c) Pull-out torque d) No load Answer: c 56.The slip frequency in an induction motor is: a) Zero b) Equal to supply frequency c) s×fs \times fs×f where s is slip and f is supply frequency d) Infinite Answer: c 57.The armature reaction in a DC machine causes: a) Increase in generated voltage b) Decrease in field flux c) Distortion and weakening of main field flux d) No effect Answer: c 58.The commutation in a DC machine is: a) Reversing current in armature conductors b) Reversing voltage in armature conductors c) Reversing current in armature conductors to maintain unidirectional torque d) None of the above Answer: c 59.The starting current of an induction motor is: a) Equal to full load current
d) Supply voltage Answer: c 65.The efficiency of a DC motor is: a) Always 100% b) Less than 50% c) Typically 85-95% d) More than 100% Answer: c 66.The slip of an induction motor is: a) Always zero b) Always one c) Between 0 and 1 d) Greater than 1 Answer: c 67.The rotor frequency in an induction motor is: a) Equal to supply frequency b) Zero c) Slip times supply frequency d) Twice supply frequency Answer: c 68.The starting torque of a squirrel cage induction motor is: a) Zero b) Low c) High d) Infinite Answer: c 69.The synchronous reactance of a synchronous machine is: a) Resistance in series with armature b) Reactance of field winding c) Combined reactance of armature leakage and reactance d) None of the above Answer: c
70.The excitation system of a synchronous generator controls: a) Speed b) Load c) Voltage d) Frequency Answer: c 71.The prime mover in a power plant is: a) Generator b) Transformer c) Mechanical device driving the generator d) Load Answer: c 72.The unit of electric power is: a) Volt b) Ampere c) Watt d) Ohm Answer: c 73.The unit of electric energy is: a) Watt b) Volt c) Kilowatt-hour (kWh) d) Ampere Answer: c 74.The power consumed in a circuit is: a) Voltage times resistance b) Current times resistance c) Voltage times current d) Voltage divided by current Answer: c 75.The maximum power transfer occurs when load resistance equals: a) Zero b) Twice source resistance
81.The starting current of an induction motor is: a) Equal to full load current b) Half of full load current c) 5 to 7 times full load current d) Zero Answer: c 82.The slip of an induction motor at synchronous speed is: a) 1 b) 0. c) 0 d) Infinity Answer: c 83.The slip of an induction motor at standstill is: a) 0 b) 0. c) 1 d) Infinity Answer: c 84.The synchronous speed of a motor with 4 poles and 50 Hz supply is: a) 1500 rpm b) 1000 rpm c) 1500 rpm d) 3000 rpm Answer: c 85.The torque-speed characteristic of a DC shunt motor is: a) Constant torque b) Torque increases with speed c) Torque decreases slightly with speed d) Torque is zero at all speeds Answer: c 86.The torque-speed characteristic of a DC series motor is: a) Constant torque b) Torque increases with speed
c) Torque decreases with speed d) Torque is zero at all speeds Answer: b 87.The armature voltage of a DC motor is: a) Equal to supply voltage b) Supply voltage minus back emf c) Supply voltage minus armature resistance drop d) Back emf Answer: c 88.The back emf in a DC motor is proportional to: a) Armature current b) Armature resistance c) Speed and field flux d) Supply voltage Answer: c 89.The efficiency of a DC motor is: a) Always 100% b) Less than 50% c) Typically 85-95% d) More than 100% Answer: c 90.The armature reaction in a DC machine causes: a) Increase in generated voltage b) Decrease in field flux c) Distortion and weakening of main field flux d) No effect Answer: c 91.The commutation in a DC machine is: a) Reversing current in armature conductors b) Reversing voltage in armature conductors c) Reversing current in armature conductors to maintain unidirectional torque
97.The back emf in a DC motor opposes: a) Armature current b) Applied voltage c) Field flux d) Load torque Answer: b 98.The commutator in a DC motor is used to: a) Increase voltage b) Decrease current c) Reverse current direction in the armature d) Store energy Answer: c 99.The slip frequency in an induction motor is: a) Zero b) Equal to supply frequency c) s×fs \times fs×f where s is slip and f is supply frequency d) Infinite Answer: c
- The maximum torque in a synchronous motor occurs at: a) Zero load b) Full load c) Pull-out torque d) No load Answer: c .
