1. The main sources of electrical energy are:
(A) Generators
(B) Batteries
(C) Solar cells
(D) All of these
2. Electric energy is measured in:
(A) Kilowatt-hour (kWh)
(B) Joules per second
(C) Amperes
(D) Volts
3. The heating effect of electric current is used in:
(A) Fan motor
(B) Electric iron
(C) Generator
(D) Transformer
4. The power consumed in a resistive load is given by:
(A) P = VI
(B) P = I²R
(C) P = V²/R
(D) All of these
5. Electric welding uses the principle of:
(A) Heating effect of current
(B) Magnetic effect of current
(C) Chemical effect of current
(D) Electrostatic effect
6. The temperature of the filament in an electric lamp is about:
(A) 2500°C
(B) 1000°C
(C) 500°C
(D) 3000°C
7. The most commonly used heating element material is:
(A) Aluminum
(B) Copper
(C) Nichrome
(D) Iron
8. The efficiency of electric heating is nearly:
(A) 80%
(B) 100%
(C) 60%
(D) 40%
9. The unit of luminous flux is:
(A) Watt
(B) Candela
(C) Lux
(D) Lumen
10. The illumination is measured in:
(A) Lux
(B) Lumen
(C) Candela
(D) Watt
11. The most efficient method of electric heating is:
(A) Resistance heating
(B) Induction heating
(C) Arc heating
(D) Dielectric heating
12. The process of melting metals using electricity is called:
(A) Arc welding
(B) Dielectric heating
(C) Electroplating
(D) Electric furnace heating
13. The material of filament in an incandescent lamp is:
(A) Tungsten
(B) Copper
(C) Aluminum
(D) Nickel
14. The efficiency of fluorescent lamps compared to incandescent lamps is:
(A) Depends on voltage
(B) Lower
(C) Equal
(D) Higher
15. The power factor of a fluorescent lamp is usually:
(A) Leading
(B) Unity
(C) Low lagging
(D) Zero
16. The light output from a 40 W fluorescent lamp is approximately:
(A) 5000 lumens
(B) 1000 lumens
(C) 400 lumens
(D) 2500 lumens
17. The main function of a choke in fluorescent lamp is to:
(A) Start lamp
(B) Limit current
(C) Reduce voltage
(D) Increase power factor
18. The heating element of an electric iron is placed:
(A) On copper plate
(B) In air
(C) Between mica sheets
(D) Inside ceramic
19. In an electric arc furnace, heat is produced by:
(A) Electric arc
(B) Resistance
(C) Induction
(D) Chemical reaction
20. The principle of electric traction is based on:
(A) Conversion of electrical to mechanical energy
(B) Conversion of mechanical to electrical energy
(C) Heating effect
(D) Magnetic field
21. The voltage used for electric traction in Pakistan is about:
(A) 11 kV AC
(B) 1.5 kV DC
(C) 25 kV AC
(D) 230 V AC
22. The main advantage of electric traction is:
(A) All of these
(B) High starting torque
(C) Low maintenance cost
(D) Pollution-free operation
23. The braking system used in electric traction is:
(A) Hydraulic braking
(B) Mechanical braking
(C) Regenerative braking
(D) Friction braking
24. The power used for domestic lighting is:
(A) Polyphase DC
(B) Three-phase AC
(C) DC supply
(D) Single-phase AC
25. The temperature rise in an electric heater depends on:
(A) Power factor
(B) Voltage only
(C) Resistance and current
(D) Material color
26. For same power, high voltage transmission reduces:
(A) Power
(B) Current
(C) Energy
(D) Resistance
27. The watt-hour meter measures:
(A) Electrical energy
(B) Power factor
(C) Voltage
(D) Frequency
28. The process of depositing a metal coating using electricity is called:
(A) Electro-refining
(B) Electrolysis
(C) Electroplating
(D) Electromagnetism
29. Electroplating is based on the:
(A) Heating effect
(B) Magnetic effect
(C) Chemical effect of current
(D) Inductive effect
30. The device used for converting light energy into electrical energy is:
(A) Dynamo
(B) Battery
(C) Solar cell
(D) Generator
31. In electric furnaces, temperature can be controlled by:
(A) Both (A) and (B)
(B) Varying voltage
(C) Varying current
(D) Mechanical means
32. The losses in electric heating equipment are mainly due to:
(A) Eddy currents
(B) Convection
(C) Conduction and radiation
(D) All of these
33. The power factor of resistance heating is:
(A) Lagging
(B) Unity
(C) Leading
(D) Zero
34. The average efficiency of electric traction motor is:
(A) 85–90%
(B) 50–60%
(C) 30–40%
(D) 95–98%
35. In an arc furnace, electrodes are usually made of:
(A) Iron
(B) Copper
(C) Graphite
(D) Zinc
36. The unit of illumination is:
(A) Lumen
(B) Lux
(C) Candela
(D) Foot-candle
37. Electric discharge lamps operate on:
(A) Ionization of gas
(B) Heating of filament
(C) Chemical reaction
(D) Electromagnetic induction
38. Sodium vapor lamps emit light of:
(A) Red color
(B) Blue color
(C) Yellow color
(D) White color
39. The arc lamps produce light due to:
(A) Gas discharge
(B) Filament heating
(C) Arc between two electrodes
(D) UV radiation
40. The life of a fluorescent lamp is approximately:
(A) 15000 hours
(B) 1000 hours
(C) 200 hours
(D) 5000 hours
41. The ratio of luminous flux to power input is called:
(A) Illumination
(B) Power factor
(C) Luminous efficiency
(D) Light factor
42. The main disadvantage of electric traction is:
(A) High initial cost
(B) Low efficiency
(C) Noise pollution
(D) Maintenance
43. The efficiency of sodium vapor lamp is about:
(A) 40–50 lumens/watt
(B) 10–15 lumens/watt
(C) 100 lumens/watt
(D) 5 lumens/watt
44. In arc welding, heat produced depends on:
(A) Current and voltage
(B) Frequency
(C) Power factor
(D) Resistance
45. The purpose of ballast in fluorescent lamp is:
(A) To reduce flicker
(B) To produce light
(C) To limit current
(D) To improve color
46. The speed of DC series traction motor is:
(A) Zero
(B) Constant
(C) Variable
(D) Infinite
47. The efficiency of electric heating depends on:
(A) Heat transfer losses
(B) Power factor
(C) Temperature
(D) Frequency
48. In electric trains, the braking energy can be:
(A) Regenerated
(B) Wasted
(C) Stored in capacitor
(D) Converted into heat
49. In domestic wiring, heating load is considered as:
(A) Reactive load
(B) Inductive load
(C) Capacitive load
(D) Resistive load
50. The main purpose of utilization of electrical energy is to convert it into:
(A) Potential energy
(B) Sound and magnetic energy only
(C) Nuclear energy
(D) Heat, light, and mechanical energy