Electricity Four and Seven Marks Questions

10th Standard

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Science

Time : 01:00:00 Hrs
Total Marks : 55
5 x 4 = 20
1. Define electric potential and potential difference.

2. State Ohm’s law.

3. Distinguish between the resistivity and conductivity of a conductor.

4. A 100 watt electric bulb is used for 5 hours daily and four 60 watt bulbs are used for 5 hours daily. Calculate the energy consumed (in kWh) in the month of January.

5. A piece of wire having a resistance R is cut into five equal parts.
a) How will the resistance of each part of the wire change compared with the original resistance?
b) If the five parts of the wire are placed in parallel, how will the resistance of the combination change?
c) What will be ratio of the effective resistance in series connection to that of the parallel connection?

6. 5 x 7 = 35
7. With the help of a circuit diagram derive the formula for the resultant resistance of three resistances connected:
a) in series and
b) in parallel.

8. a) What is meant by electric current?
b) Name and define its unit.
c) Which instrument is used to measure the electric current? How should it be connected in a circuit?

9. a) State Joule’s law of heating.
b) An alloy of nickel and chromium is used as the heating element. Why?
c) How does a fuse wire protect electrical appliances?

10. a) What are the advantages of LED TV over the normal TV?
b) List the merits of LED bulb.

11. A piece of wire of resistance 10 ohm is drawn out so that its length is increased to three times its original length. Calculate the new resistance.