### GK QUESTIONS ON ELECTRICITY

1. Which one among the following is the correct order of power consumption for light of equal intensity?

1. CFL tube < Fluorescent tube < Incandescent bulb < Light emitting diode
2. Light emitting diode < CFL tube < Fluorescent tube < Incandescent bulb
3. CFL tube < Fluorescent tube < Light emitting diode < Incandescent bulb
4. Incandescent bulb < Light emitting diode < Fluorescent tube < CFL tube

2. In India, distribution of electricity for domestic purpose is done in the form of

1. 220 V; 50 Hz
2. 110 V; 60 Hz
3. 220 V; 60 Hz
4. 110 V; 50 Hz

3. When an electrical safety fuse is rated (marked) as 16 A, it means it

1. will not work if current is less than 16 A
2. has a resistance of 16 Ω
3. will work if the temperature is more than 16°C
4. will be blown (break) if current exceeds 16 A

4. The main power supply in India is at 220 V, whereas that in the US is at 110 V. Which one among the following statements in this regard is correct?

1. 110 V is safer but more expensive to maintain
2. 110 V is safer and cheaper to maintain
3. 110 V leads to lower power loss
4. 110 V works better at higher latitudes

5. Two similarly charged bodies are kept 5 cm apart in air. If the second body is shifted away from the first by another 5 cm, their force of repulsion will be

1. doubled
2. halved
4. reduced to one-fourth

6. The resistance of a wire is 10Ω. If it is stretched ten times, the resistance will be

1. 1 Ω
2. 10 Ω
3. 100 Ω
4. 1000 Ω

7. A house, served by a 220 V supply line, is protected by a 9 A fuse. What is the maximum number of 60 watt bulbs that can be turned on in parallel?

1. 11
2. 22
3. 33
4. 44

8. Two metallic wires A and B are of same material and have equal length. If the cross-sectional area of B is double that of A, then which one among the following is the electrical resistance of B?

1. Twice that of A
2. 4 times that of A
3. 1/4 that of A
4. 1/2 that of A

9. Three resistance coils of 1 Ω, 2 Ω and 3 Ω are connected in series. If the combination is connected to a battery of 9 V, what is the potential drop across the resistance coil of 3 Ω ?

1. 2.0 volt
2. 3.0 volt
3. 4.5 volt
4. 6.0 volt

10. An electric lamp of 100 watt is used for 10 hours per day. The ‘units’ of energy consumed in one day by the lamp is

1. 1 unit
2. 0.1 unit
3. 10 units
4. 100 units

11. An electric iron of resistance 20 W takes a current of 5 A. The heat developed in joules in 30 s is

1. 5 kJ
2. 10 kJ
3. 15 kJ
4. 20 kJ

12. Kilowatt-hour is the unit of

1. potential difference
2. electric power
3. electric energy
4. electric potential

13. Two copper wires A and B of length L and 2L respectively, have the same area of cross-section. The ratio of the resistivity of wire A to the resistivity of wire B is

1. 4
2. 2
3. 1
4. 1/2

14. If the electrical resistance of a typical substance suddenly drops to zero, then the substance is called

1. super conductor
2. semiconductor
3. conductor
4. insulator

15. The material used for electric fuse is an alloy of tin and lead. This alloy should have

1. high specific resistance and low melting point
2. low specific resistance and high melting point
3. low specific resistance and low melting point
4. high specific resistance and high melting point

16. Capacity of a parallel plate condenser can be doubled by:

1. doubling the areas of the plates
2. doubling the distance of separation between the plates
3. reducing the distance of separation between the plates to half the original separation
4. doubling both the areas of the plates and the distance of separation between the plates

Select the correct answer using the code given below:

1. 1 and 4
2. 1 and 3
3. 3 only
4. 2 and 3

17. If two conducting spheres are separately charged and then brought in contact:

1. the total energy of the two spheres is conserved
2. the total charge on the spheres is conserved
3. both the total energy and charge are conserved
4. the final potential is always the mean of the original potential of the two spheres

18. Two pieces of metallic wire having equal length and equal volume placed in air have different resistances. The two wires must:

1. have different cross sections
2. have different temperatures
3. be of different materials
4. be of same density

19. If a heater coil is cut into two equal parts and only one part is used in the heater, the heat generated will be:

1. doubled
2. four times
3. one-fourth
4. halved

20. A hollow metal ball carrying an electric charge produces no electric field at points:

1. outside the sphere
2. on its surface
3. inside the sphere
4. only at the centre

21. Microwave oven consumes less power due to:

3. large frequency as well as wavelength of radiation
4. small frequency as well as wavelength of radiation

22. How many sixty watt (60 W) bulbs may be safely used in a 240-V supply with 4-ampere fuse?

1. 4
2. 8
3. 12
4. 16

23. The effective resistance of three equal resistances, each of resistance r, connected in parallel, is

1. 3/r
2. r/3
3. 3r
4. r3

24. The specific resistance of a conducting wire depends upon

1. length of the wire, area of cross-section of the wire and material of the wire
2. length of the wire and area of cross-section of the wire but not on the material of the wire
3. material of the wire only but neither on the length of the wire nor on the area of cross-section of the wire
4. length of the wire only but neither on the area of cross-section of the wire nor on the material of the wire

25. Net charge in a current-carrying conductor is

1. always positive
2. always negative
3. zero
4. either positive or negative

26. Which one of the following is the resistance that must be placed parallel with 12 Ω resistance to obtain a combined resistance of 4 Ω?

1. 2 Ω
2. 4 Ω
3. 6 Ω
4. 8 Ω