# Assignment-2 (Electricity)

## Very Short Answer Type Questions:

1. Define electric work.
2. What is the unit of electric work? Define it, in relation to quantity of charge and potential difference.
3. Name two bigger units of electric work.
4. What do you understand by the term current electricity?
5. Define the term “electric current”.
6. How is an ammeter connected in an electric circuit so as to measure electric  current?
7. What is the unit of electric charge? How much electric charge is on one electron?
8. If 12 J of work is done in moving 2 coulomb of electric charge through a conductor, what is the potential difference at the ends of the conductor?
9. State and define the SI unit of potential difference.
10. State SI unit of electric power.
11. Define the SI unit of electric power.
12. Name and define the smallest commercial unit of electricity.
13. Define kWh.
14. Prove : 1 kWh = 3.6 MJ.
15. Name two common materials used as heating elements.

16. Name a metal which is used as filament in an electric bulb.
17. What do you understand by the term fuse in an electric circuit?
18. State the composition of material of the fuse wire.
19. Where is a fuse placed in an electric circuit?
20. A bulb in an electric circuit is glowing. Is it a close or open electric circuit?
21. What do you understand by the term electric resistance?
22. How does electric resistance change with the change in the length of conductor?
23. How does electric resistance change with the change in the area of cross-section of conductor?
24. How does electric resistance of solid ionic compounds compare with respect to molten compounds?
25. Why does a conducting wire offer resistance to the flow of electrons?
26. What do you understand by the term electric potential?
27. What do you understand by the term potential difference?

## Questions From CBSE Examinations:

1. Two resistors of 20 Ω and 40 Ω are connected in parallel in an electric circuit. How does the current passing through the two resistors compare?
2. Two resistors of 30 Ω and 60 Ω are connected in parallel in an electric circuit. How does the current passing through the two resistors compare?
3. Define electric circuit. Distinguish between open and closed circuit.
4. What is the lowest resistance that can be obtained by combining four coils of resistors of 4 Ω, 8 Ω, 12 Ω and 24 Ω?
5. Write a mathematical expression for Joule’s law of heating. Name one device which works on this principle.
6. What happens to the resistance of a conductor when the length of the conductor is reduced to half?
7. Define the SI unit of resistance.
8. What happens to resistance of a conductor when temperature is increased?
9. What is electrical resistivity? In a series electrical circuit comprising a resistor made up of a metallic wire, the ammeter reads 5 A. The reading of the ammeter decreases to half when the length of the wire is doubled. Why?
10. What is the minimum resistance which can be made using five resistors each of 1/5Ω?
11. You have two metallic wires of resistances 6 ohm and 3 ohm. How will you connect these wires to get the effective resistance of 2 ohm?
12. Draw a schematic diagram of a circuit consisting of a cell of 1.5 V, 10 Ω resistor and 15 Ω resistor and a plug key, all connected in series.
13. Name the instrument used to measure electric current in a circuit.
14. The voltage-current (V-I) graph of a metallic circuit at two different temperatures T1 and T2 is shown, which of the two temperatures is higher and why? 15. What is meant by saying that the potential difference between two points is 1V?
[2010 (T-I)]
16. A wire of resistivity ‘r’ is pulled to double its length. What will be its new resistivity?
[2010 (T-I)]
17. Name the physical quantity whose unit is Volt/ ampere. [2010 (T-I)]
18. Why do we use copper and aluminium wire for transmission of electric current? [2010 (T-I)]
19. What is commercial unit of energy?
[2010 (T-I)]
20. Name the instrument used for measuring:
(i) potential difference
(ii) current
21. Define Ohm’s Law.
22. How is a Voltmeter connected in the circuit to measure the potential difference between two points?
23. How is an ammeter connected in the circuit to measure current flowing through a conductor?
24. Nichrome is used to make the elements of electric heater. Why?
25. Calculate the energy consumed by 1200 W toaster in 200 minutes.
26. A lamp rated 100 W and 220 V is connected to mains electric supply. What current is drawn from the supply line, if the voltage is 220 V?

27. Out of 60 W and 40 W lamps, which one has higher resistance when we use?
28. If the distance between two electric charges is doubled, how much will the force exerting between them change to?
29. Should the heating element of an electric iron be made of iron, silver or nichrome wire?
30. Define the term ‘resistivity’ of a material.
31. Calculate the resistance of a conductor, if the current flowing through it is 0.2 A when the applied potential difference is 0.8 volt.