Question

Which of the following statements is true about Planck's Law?

A.
The frequency of the emitted light is inversely proportional to the energy given off by the electrons.

B.
The frequency of the emitted light is directly proportional to the energy given off by the electrons.

C.
The wavelength of the emitted light is directly proportional to the energy given off by the electrons.

D.
The wavelength of the emitted light is inversely proportional to the energy given off by the electrons

Answer 1

answer : option (B) The frequency of emitted light is directly proportional to the energy given off by the electrons.

explanation : according to Plank's quantum theory,

when a beam of light of specific frequency strikes into the metal surface, photons eject from the surface by taking some amount of energy.

here, Let energy of incident photon = E

threshold energy, $\Phi$

from Plank's theory,

energy of emitted photon = $E -\Phi$

or, $h\nu=E-\Phi$

it is clear that the frequency of emitted light is directly proportional to E (i.e., energy given off by the electrons ).