Question

How is Planck’s constant used in the photoelectric effect?

Answer 1

Photoelectric effect tells us the particle nature of light. This phenomenon uses electrons ejected from the metals. This method is employed in making various devices.

Complete step-by-step answer: Photoelectric effect is the phenomena when the surface of a metal emits or ejects electrons due to a light striking the surface of the metal. This light has a suitable frequency, and on this frequency only the emission can occur. This frequency is known as threshold frequency, denoted by ${{\nu }^{0}}$.
The energy of the radiation of photoelectrons is such that it is directly proportional to the frequency of the emitted photons.
So, $E\,\propto \,\nu$
When we replace the proportionality sign, ‘h’ symbol comes to its place. This symbol ‘h’ is called Planck's constant. So, the equation becomes:
$E\,=h.\,\nu$
The value of Planck’s constant, h is 6.626 $\times {{10}^{-34}}$ Joule-sec. and E is the energy of emission while $\nu$ is the frequency of the emitted electron.
Hence, Planck’s constant in photoelectric effect is multiplied by the frequency of the emitted photon.

Additional information: alkali metals like, potassium, cesium, etc. shows strong photoelectric effect due their large size. Photoelectric effect is applied in solar panels, light detectors, photoelectric cells.

Note: When the electrons are emitted from the metal, the emitted electrons are called photons or photoelectrons. More the frequency of light falls on the metal, the more is the kinetic energy of these photons. These photons get emitted only at the threshold frequency, this is the minimum frequency for emission.