Question

An electron of mass m and charge e initially at rest gets accelerated by a constant field E. The rate of change of a de-Broglie wavelength of the electron with time is given by (relativistic variation of mass with time is to be ignored).

Answer 1

Correct option : (4)

Explanation :

When an electrons is accelerated through a electric field we have F = eE

and the acceleration of the electron is given by a = eE/m

Hence the velocity of the electron after it has remained in the field for a time t is given v = eEt/m

The wavelength of the deBroglie wave associated with this electron is λ = h/mv = h/eEt