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Current Electricity

Question

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Explain how does the resistivity of a conductor depend upon (i) number density n of free electrons, and (ii) relaxation time t.

Solution

Resistivity ρ of a metal conductor is given by,

ρ = \frac{m}{{ne}^{2} t}

i.e.,

ρα = \frac{1}{n}

and

ρ α \frac{1}{t}

Some More Questions From Current Electricity Chapter

What conclusion can you draw from the following observations on a resistor made of alloy manganin?

Current A

Voltage V

Current A

Voltage V

0.2

0.4

0.6

0.8

1.0

2.0

3.94

7.87

11.8

15.7

19.7

39.4

3.0

4.0

5.0

6.0

7.0

8.0

59.2

78.8

98.6

118.5

138.2

158.0

Answer the following questions:
A steady current flows in a metallic conductor of non-uniform cross-section. Which of these quantities is constant along the conductor: current, current density, electric field, drift speed?

Answer the following questions:
Is Ohm’s law universally applicable for all conducting elements? If not, give examples of elements which do not obey Ohm’s law.

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