How does the mobility of electrons in a conductor change, if the potential difference applied across the conductor is doubled, keeping the length and temperature of the conductor constant?
Mobility
Where vd is the drift velocity and E is the electric field.
Drift velocity
Substituting this value in the equation of mobility
If the temperature and length of the conductor are constant there is no change in the relaxation time . And also mobility is independent of potential difference. So there is no change in mobility of electrons if the potential difference is changed keeping the length and temperature constant.
Potential difference is inversely proportional to mobility. Hence, when potential difference is doubled mobility is halved