Q47: Mobility of electrons: A. decreases with increase in potential difference... - Current Electricity - Physics CUET UG 02-07-2023 Shift 3 Paper | Agrigyan

Mobility of electrons $\mu$ is defined as the magnitude of drift velocity per unit electric field:

• Dependence on Electric Field / Potential Difference: Since drift velocity $v_d = \frac{e E \tau}{m}$ is directly proportional to electric field $E = \frac{V}{L}$, the ratio $\frac{v_d}{E}$ is independent of the applied electric field and potential difference. Thus, statement C is correct, while A and B are incorrect.
• Dependence on Temperature: As temperature increases, lattice ions vibrate more vigorously, reducing the average relaxation time $\tau$, which decreases mobility ($\mu \propto \tau$). Conversely, as temperature decreases, $\tau$ increases, so mobility increases. Thus, statement D and E are incorrect.