Consider a beam of electrons (each electron with energy `E_(0))` incident on a metal surface kept in an evacuated chamber. Then

Options

A. no electrons will be emitted as only photons can emit electrons.
B. electrons can be emitted by all with an energy, `E_(0)`.
C. electrons can be emitted with any energy, with a maximum of `E_(0)-phi (phi ` is the work function).
D. electrons can be emitted with any energy, with a maximum of `E_(0)`.

Answer

D

Explanation

When abeam of electrons of energy `E_(0)` is incident on a metal surface kept in an evacuated chamber, electrons can be emitted with maximum energy `E_(0)` (due to elastic collision) and with any energy less than `E_(0)`, when part of incident energy of electron is used in liberating the electrons from the surface of metal.