Question

Consider a beam of electrons (each electron with energy $E_0$) incident on a metal surface kept in an evacuated chamber. Then

• A. no electrons will be emitted as only photons can emit electrons
• B. electrons can be emitted but all with an energy $E_0$
• C. electrons can be emitted with any energy, with a maximum of $E_0-\varphi$ ($\varphi$ is the work function)
• D. electrons can be emitted with any energy, with a maximum of $E_0$

Answer 1

Answer: (D)

When a beam 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.