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

Options

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

Answer

B

Explanation

When the temperature increases , resistance increases . As the e.mf. Applied is the same , the current density decreases . The drift velocity decreases . But the rms velocity of the electron due to thermal motion is proportional to `sqrt(T)` . The thermal velocity increases.