Question

Einstein’s photoelectric equation states that \[{E_K} = h\nu - W\], In this equation what does \[{E_K}\]​ refer to.
A. Kinetic energy of all ejected electrons
B. Mean kinetic energy of emitted electrons
C. Minimum kinetic energy of emitted electrons
D. Maximum kinetic energy of emitted electrons

Answer 1

Hint:When a photon falls on the metal surface, the entire energy of the photon is transferred to the electron. As a result, a part of this energy is used to remove the electron from the metal atoms, and the rest is given to the ejected electron as kinetic energy. This is the basis for Einstein's photoelectric equation.

Formula Used:
Einstein’s photoelectric equation is given by,
\[{E_K} = h\nu - W\]
Where, W is the work function, h is Planck’s constant and \[\nu \] is frequency.

Complete step by step solution:
Einstein’s photoelectric equation is given by,
\[{E_K} = h\nu - W\]
Here, W is the work function, which is the minimum energy required to emit out the electron and \[h\nu \] is the energy of the photon where the energy is provided to the electron by the photon.

Suppose if you consider an electron on the surface of some metal, when the photon strikes this electron, photons give the energy which is equal to the work function in order to emit out electrons and the remaining energy is \[h\nu \] in the form of kinetic energy.

All the electrons will not gain the kinetic energy, that is, all the electrons will not absorb the photon to get excited from a surface and only a few electrons will gain some kinetic energy therefore, here the kinetic energy is maximum. This means the electron cannot have kinetic energy beyond this value. Therefore, \[{E_K}\] refers to the maximum kinetic energy of emitted electrons.

Hence, option D is the correct answer.

Note:Remember the formula of the kinetic energy and also the formula of the energy of the photon because these formulas are very important in solving these types of problems.