Potential at a point A is ` 3` volt and at a pont `B` is ` 7 volt`, an electron is moving towards `A` form `B`.

Options

A. It must have some K.E. at B to reach A
B. It need not have any K.E. at B to reach A
C. to reach A it must have more than or equal to 4e V K.E. at B.
D. when it will reach A it will have K.E. more then or at least equal to `4 eV` if it was released from rest at B.

Answer

A, C

Explanation

Field is in same direction
`U_A =- 3e V, U_B =- 7eV`
For `B` to `A` it is moving towards higher potential energy
`{:[K_f -K_i = U_i -U_f],[K_f= (U_i -U-f) +K_i],[K_f=4eV + K_i]:}`.