#### Electricity Two Marks Question

10th Standard

Reg.No. :
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Science

Time : 00:45:00 Hrs
Total Marks : 30
15 x 2 = 30
1. Define the unit of current.

2. Why is tungsten metal used in bulbs, but not in fuse wires?

3. What is the difference between open and dosed circuits?

4. Write the difference between ammeter and voltmeter

5. Write the difference between conductor and insulator.

6. Out of 100 W and 40 W bulbs) which has high electrical resistance when in use.

7. Draw a closed circuit diagram consisting of resistor, ammeter, voltmeter cell and a point key

8. Write electrical use of the components in electrical circuit.

9. Find the total resistance of parallel connection of series resistors?

10. Derive the equation of Ioule's law of heating.

11. How does a parallel circuit differ from a series circuit?

12. Electrical resistivities of some substances at 200 C are given below:

 Silver 1.60 x 10-8Ω- m Copper 1.62x10-8Ω-m Tungsten 5.20 x 10-8Ω - m Iron 10.0 x 10-8Ω-m Mercury 94.0 x 10-8Ω-m Nichrome 10.0 x 10-8Ω-m

Answer the following question in relation to them:
(i) Among silver and copper, which one is a better conductor? Why?
(ii) Which material would you advise to be used in electrical heating devices? Why?

13. Two metallic wires A and B are connected in series. Wire A has length l and radius r, while wire B has length 2l and radius 2r. Find the ratio of the total resistance of series combination and the resistance of wire A, if both the wires are of same material.

14. The electric power consumed by a device may be calculated by using either of the two expressions : P = I ^2 R or P = V ^ 2/R. The first expression indicates that the power is directly proportional to R, whereas the second expression indicates inverse proportionally. How can the seemingly different dependence of P on R in these expression be explained?

15. V-I graphs for the two wires A and Bare shown in the figure. If we connect both the wires one by one to the same battery, which of the two will produce more heat per unit time? Give justification for your answer.