Question

The Planck’s constant is $h$ and frequency of a photon is $v$, then write the formula for Einstein photoelectric equation.

Answer 1

Hint: Maxwell gave the theory of light being an electromagnetic wave and it was Planck’s idea that light also has particle nature. Einstein later used these ideas to explain the photoelectric effect documented by Heinrich Hertz.

Complete step by step solution:
When lights of sufficient frequency are incident on a metal surface, electrons are emitted, this phenomenon is known as the photoelectric effect.
This effect was explained by Einstein using the revolutionary idea of Planck in which he stated light as a particle. Each particle of light carries some energy (called photon or quanta), which depends upon the frequency of light and is mathematically given as,
$E=hv$, where E is the energy carried by the photon, $h$ is the Planck’s constant having a value of $6.63\times 10^{-34}$ Js and $v$ is the frequency of light.
Hence, the required expression is $E=hv$.

Additional information:
The photoelectric effect was first given by Heinrich Hertz but the observations made by him failed to be explained by Maxwell's theory of light being an electromagnetic wave.
According to the theory given by Einstein, light has been considered as the bundle of photons, which when fall on a metal surface, transfers all its energy to the electrons. From the energy transferred, a part of it used up to remove the electron and remaining is saved as kinetic energy.

Note: Energy of a light wave also depends on its intensity. As the intensity of the light wave increases, the number of photons will also increase and thus the total energy of the light wave will increase.