NEET Physics Question - Current Electricity - Variation of Resistance with Temperature

Assertion (A): Drift velocity of \(e^-\) in a metallic wire will decrease if temperature of wire is increased.

Reason (R): On increasing temperature conductivity of metallic wire decreases.

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:

When temperature increases, thermal vibrations of atoms in the conductor increase, leading to more frequent collisions for electrons. This reduces the relaxation time \(\tau\), which in turn decreases the drift velocity \(v_d = \frac{eE\tau}{m}\). Decreased drift velocity leads to decreased conductivity \(\sigma = \frac{ne^2\tau}{m}\). Thus, both (A) and (R) are true, and (R) is the correct explanation for (A).

Rankers Physics

Drift Velocity and Temperature

Solution:

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