COMEDK · Physics · 19. Current Electricity

A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it

A increases, thermal velocity of the electron decreases
B decreases, thermal velocity of the electron decreases
C increases, thermal velocity of the electron increases
D decreases, thermal velocity of the electron increases

Verified Solution

Answer & Solution

Correct Answer

(D) decreases, thermal velocity of the electron increases

Step-by-step Solution

Detailed explanation

Drift velocity of the electron is given as \[ v_{d}=\frac{e E \tau}{m} \] where, \(e=\) charge on electron, \(E=\) electric field, \(\tau=\) relaxation time and \(m=\) mass of the electron. Since, \[ \therefore \quad v_{d}=\frac{e V \tau}{m l} \] Since, \(e, V, m\) and \(l\) are…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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