Page 64 - CHAPTER-1 (Electricity)
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CHAPTER 1
ELECTRICITY
7. Out of the two wires P and Q shown below, which one has greater
resistance? Justify it.
8. What happens to the resistance of a conductor when its area of
cross-section is increased?
9. The radius of conducting wire is doubled. What will be the ratio of
its new specific resistance to the old one?
10. Resistance of an incandescent filament of a lamp is comparatively
much more than that when it is at room temperature. Why?
11. Why is maganin used for making standard resistors?
12. A resistance of 1 k Ω has a current of 0.25 A throughout it when it is
connected to the terminals of a battery. What is the potential
difference across the ends of a resistor?
13. Calculate the current in a circuit if 500 C of charge passes through
it in 10 minutes.
14. An electric iron draws a current of 0.6 A when the voltage is 100 volt.
Calculate the amount of electric charge flowing through it in one
hour.
15. Define the term resistivity.
16. Write S.I. unit of resistivity.
17. How will the resistivity of a conductor change when its length is
tripled by stretching it?
18. When a battery is connected to a closed circuit, charges flow in the
circuit almost instantaneously. Explain.
19. Why is closed path required for the flow of current?
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