Name: Revisiting Ohm's Law & Resistivity
Uploaded: 2019-07-19
Duration: 4 min 5 s
Description: The entire domain of the science of electric current can be explained using Ohm’s law, that’s how powerful this discovery was. We will revise this once again.

Question

Give a brief account of the factors on which the resistance of a conductor depends.

Accepted Answer

Resistance is the property of a conductor that opposes the flow of current through it.

The following factors affect the electrical resistance of a conductor:

Temperature of the conductor

Length of the conductor

Nature of the material of the conductor

Area of cross-section of the conductor or thickness of the conductor

Effect of Temperature of the Conductor: The resistance of all pure metal increases with increase in temperature and on the other hand it, decreases on lowering the temperature. However, the resistance of alloys like Nichrome, Manganin remains almost unaffected by temperature.

Effect of Length of the Conductor: The length of a wire increases, its resistance also increases and when the length of a wire decreases, its resistance also decreases. This means that the resistance of a conductor (R) is directly proportional to its length l.

Effect of the Nature of the Material of the Conductor: This shows that the resistance depends on the nature of the material of the conductor.

Effect of Area of Cross-section of the Conductor: The area of cross-section of a conductor increases, its resistance decreases and when the area of cross-section of a conductor decreases, its resistance increases. This means that the resistance of a conductor (R) is inversely proportional to its area of cross-section (A).
Thus, a thick wire has less resistance whereas a thin wire has more resistance.

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