Temperature Coefficient of Resistance – Rankers Physics

Properties of Semiconductors: Practice Problem & Solution

Assertion (A): The temperature coefficient of resistance is positive for metals and negative for semiconductors. Reason (R): On raising the temperature, in metals drift velocity increases but in semiconductors more charge carriers are released.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Properties of Semiconductors. Understanding the underlying formula is key to arriving at the correct answer below:

Concept: Temperature dependence of resistance.
Metals have a positive temperature coefficient of resistance, while semiconductors have a negative one, so (A) is true. In metals, drift velocity *decreases* with increasing temperature due to increased scattering. In semiconductors, carrier concentration increases, so (R) is false.

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