Question

The velocity of the photoelectrons emitted from a surface depends upon the ______.

Options

• Wavelength of incident radiation only

• Intensity of incident radiation only

• Work function of the surface only

• Both wavelength of the incident radiation and work function of the surface

Answer 1

The velocity of the photoelectrons emitted from a surface depends upon the both wavelength of the incident radiation and work function of the surface.

Explanation:

According to Einstein’s photoelectric equation:

K_max = hν − ϕ

The speed of photoelectrons depends on their kinetic energy:

K = `1/2  mv^2`

Therefore, the velocity depends on:

• The frequency (or wavelength) of the incident radiation.
• The work function of the material.

The effect of intensity influences the number of electrons emitted, but it does not affect their velocity.

Final Relation:

v = `sqrt(hv - ϕ)`

Hence, the velocity depends on both the wavelength (or frequency) of the incident light and the work function of the surface.