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# Important questions class 12 physics Current Electricity

Updated: Apr 30, 2020

## Current Electricity

[1 Mark Questions]

1. Plot a graph showing the variation of current versus voltage for the material GaAs.

2. Show a variation of resistivity of copper as a function of temperature in the graph.

3. Define the term drift velocity of charge carriers in a conductor and write its relationship with the current flowing through it.

4. Define the term and electrical conductivity of a metallic wire. Write its SI unit.

5. Show a variation of resistivity of Si with temperature in the graph.

6. Define the term mobility of charge carriers in a conductor. Write its SI unit.

7. Write a relation between the current and drift velocity of electrons in a conductor. Use this relation to explain how the resistance of a conductor changes with the rise in temperature.

8. When electrons drift in metal from lower to higher potential, does it mean that all the free electrons of the metal are moving in the same direction?

9. Show on a graph, the variation of resistivity with temperature for a typical semiconductor.

10. Two wires of equal length, one of copper and the other of manganin have the same resistance. Which wire is thicker?

11. Define the resistivity of a conductor. Write its SI unit.

12. Two identical slabs, of a given metal, are joined together, in two different ways, as shown in the figure. What is the ratio of the resistances of these two combinations?

13. Two conducting wires X and Y of the same diameter but different materials are joined in series across a battery. If the number density of electrons in X is twice that in Y, then find the ratio of the drift velocity of electrons in the two wires.

14. The three colored bands, on a carbon resistor, are red, green and yellow respectively. Write the value of its resistance.

15. Write an expression for the resistivity of a metallic conductor showing its variation over a limited range of temperatures.

16. Define ionic mobility. Write its SI unit.

17. A physical quantity, associated with electrical conductivity, has the SI unitΩm. Identify this physical quantity.

18. State the underlying principle of a potentiometer.

19. Two identical cells, each of emf E, having negligible internal resistance, are connected in parallel with each