1. The SI unit of electric charge is:
(A) Ampere
(B) Coulomb
(C) Volt
(D) Ohm
2. Ohm’s law defines the relationship between:
(A) Voltage, Current, and Resistance
(B) Power, Energy, and Time
(C) Charge, Energy, and Force
(D) Resistance, Capacitance, and Inductance
3. The instrument used to measure current is called a:
(A) Voltmeter
(B) Wattmeter
(C) Ammeter
(D) Galvanometer
4. One kilowatt is equal to how many watts?
(A) 10 W
(B) 100 W
(C) 1000 W
(D) 10,000 W
5. The resistance of a wire depends on:
(A) Length only
(B) Length, area, and material
(C) Material only
(D) Current through the wire
6. The reciprocal of resistance is called:
(A) Impedance
(B) Conductance
(C) Reactance
(D) Capacitance
7. The unit of electric power is:
(A) Watt
(B) Joule
(C) Ampere
(D) Ohm
8. Which of the following is a good conductor of electricity?
(A) Rubber
(B) Plastic
(C) Glass
(D) Copper
9. The potential difference is measured in:
(A) Volt
(B) Ampere
(C) Joule
(D) Watt
10. Kirchhoff’s current law (KCL) is based on the law of:
(A) Conservation of charge
(B) Conservation of energy
(C) Conservation of mass
(D) Conservation of momentum
11. The direction of conventional current is from:
(A) Negative to positive
(B) Positive to negative
(C) Ground to neutral
(D) None of these
12. The power dissipated in a resistor is given by:
(A) VI
(B) I²R
(C) V²/R
(D) All of these
13. The unit of capacitance is:
(A) Weber
(B) Henry
(C) Ohm
(D) Farad
14. The energy stored in a capacitor is:
(A) ½ CV²
(B) ½ LI²
(C) VI
(D) V²/R
15. In an inductor, energy is stored in the form of:
(A) Heat
(B) Magnetic field
(C) Electric field
(D) Chemical energy
16. The phase difference between current and voltage in a pure resistor is:
(A) 0°
(B) 45°
(C) 90°
(D) 180°
17. The power factor of a purely inductive circuit is:
(A) 1
(B) 0
(C) 0.5
(D) 0.707
18. The frequency of AC supply in Pakistan is:
(A) 40 Hz
(B) 60 Hz
(C) 50 Hz
(D) 55 Hz
19. The component that opposes any change in current is:
(A) Resistor
(B) Transformer
(C) Capacitor
(D) Inductor
20. The main function of a transformer is to:
(A) Store energy
(B) Convert DC to AC
(C) Step up or step down voltage
(D) Convert mechanical energy to electrical energy
21. The core of a transformer is made of:
(A) Aluminum
(B) Copper
(C) Laminated iron
(D) Wood
22. The efficiency of an ideal transformer is:
(A) 0%
(B) 100%
(C) 75%
(D) 90%
23. Electric energy is measured in:
(A) Watts
(B) Watt-hour
(C) Joules
(D) Ohms
24. The instrument used to measure resistance is called:
(A) Voltmeter
(B) Ohmmeter
(C) Ammeter
(D) Wattmeter
25. In a series circuit, the current is:
(A) Same through all components
(B) Different in each component
(C) Zero
(D) Infinite
26. In a parallel circuit, the voltage across each branch is:
(A) Zero
(B) Variable
(C) Different
(D) Same
27. The reactance of a capacitor decreases when frequency:
(A) Increases
(B) Decreases
(C) Remains constant
(D) Doubles
28. The reactance of an inductor increases when frequency:
(A) Becomes zero
(B) Decreases
(C) Remains constant
(D) Increases
29. The total resistance of parallel resistors is:
(A) Less than the smallest resistor
(B) Equal to the largest resistor
(C) Greater than the largest resistor
(D) None of these
30. Power factor is given by:
(A) sinθ
(B) tanθ
(C) cosθ
(D) cotθ
31. The unit of magnetic flux is:
(A) Tesla
(B) Coulomb
(C) Henry
(D) Weber
32. 1 Henry equals:
(A) 1 Wb/A
(B) 1 V/A
(C) 1 Ω
(D) 1 A/Wb
33. A device that converts mechanical energy into electrical energy is:
(A) Motor
(B) Generator
(C) Transformer
(D) Battery
34. A DC motor converts:
(A) Electrical to mechanical energy
(B) Mechanical to electrical energy
(C) Heat to electricity
(D) AC to DC
35. The main cause of eddy current losses in transformers is:
(A) Thick core laminations
(B) Magnetic leakage
(C) Unlaminated iron core
(D) Copper windings
36. The unit of inductive reactance is:
(A) Ohm
(B) Henry
(C) Farad
(D) Weber
37. In a purely capacitive circuit, current leads voltage by:
(A) 180°
(B) 0°
(C) 45°
(D) 90°
38. The symbol “μF” stands for:
(A) Milli Farad
(B) Mega Farad
(C) Micro Farad
(D) Nano Farad
39. Electrical power (P) is equal to:
(A) IR
(B) VI
(C) V/I
(D) I²R²
40. The current that reverses direction periodically is called:
(A) Direct Current
(B) Alternating Current
(C) Pulsating Current
(D) Constant Current
41. The device that stores charge is:
(A) Inductor
(B) Transformer
(C) Resistor
(D) Capacitor
42. The instrument used to measure potential difference is:
(A) Voltmeter
(B) Ammeter
(C) Wattmeter
(D) Ohmmeter
43. Which law states that current is directly proportional to voltage?
(A) Ohm’s Law
(B) Faraday’s Law
(C) Lenz’s Law
(D) Coulomb’s Law
44. Which material is used for making electric bulbs’ filament?
(A) Copper
(B) Aluminum
(C) Tungsten
(D) Nickel
45. Insulators have:
(A) Low resistance
(B) High resistance
(C) Zero resistance
(D) Infinite conductivity
46. A fuse wire is made of:
(A) Lead-tin alloy
(B) Iron
(C) Copper
(D) Steel
47. The heating effect of current is used in:
(A) Electric motor
(B) Electric iron
(C) Transformer
(D) Generator
48. The efficiency of a machine is always:
(A) More than 100%
(B) Equal to 100%
(C) Less than 100%
(D) Zero
49. The device that converts AC into DC is:
(A) Transformer
(B) Rectifier
(C) Generator
(D) Inverter
50. Electric current is measured in:
(A) Joules
(B) Amperes
(C) Volts
(D) Watts