Explain Einstein's photoelectric equations on
the basis of planck's quantum theory.
Answers
Explanation:
According to this theory, radiation from a source is not emitted continuously, but it is emitted in packets or bundles of energy. ... If the radiation is of frequency ν, each quantum has energy where h is Planck's constant. Thus energy of photon = E = hν The energy is emitted in a discontinuous manner.Photoelectric effect can only be explained by the quantum concept of radiation. ... 2) The magnitude of stopping potential and hence the maximum kinetic energy of emitted photoelectrons is proportional to the frequency of emitted radiation.Einstein’s photoelectric equation,
K
max
=hν−ϕ
0
where
K
max
is the max kinetic energy of emitted electrons and ϕ
0
is the work function.
According to Planck’s quantum theory, light radiations consist of small packets of energy. Einstein postulated that a photon of energy hv is absorbed by the electron of the metal surface, then the energy is used to liberate electron from the surface and rest of the energy becomes the kinetic energy of the electron.
Energy of photon is,
E=hv
Where, h = Planck’s constant
v = frequency of light
The minimum energy required by the electron of a material to escape out of it, is work function.
The additional energy acquired by the electron appears as the maximum kinetic energy ‘Kmax’ of the electron.
Einstein's photoelectric equation
K
max
=eV
o
Salient features observed in photoelectric effect: —
The stopping potential and hence the maximum kinetic energy of emitted electrons varies linearly with the frequency of incident radiation.
There exists a minimum cut - off frequency , for which the stopping potential is zero.
Photoelectric emission is instantaneous.