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प्रश्न
- In the explanation of photo electric effect, we assume one photon of frequency ν collides with an electron and transfers its energy. This leads to the equation for the maximum energy Emax of the emitted electron as Emax = hν – φ0 where φ0 is the work function of the metal. If an electron absorbs 2 photons (each of frequency ν) what will be the maximum energy for the emitted electron?
- Why is this fact (two photon absorption) not taken into consideration in our discussion of the stopping potential?
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उत्तर
According to Einstein, photoelectric effect is the result of one to one inelastic collision between photon and electron in which the photon is completely absorbed.
Einstein's photoelectric equation is E = W0 + Kmax
Where `K_("max") = 1/2 mv_("max")^2` = maximum kinetic energy of emitted electrons
And W0 = Work function (or threshold energy)
`W_0 = hv_0 = (hc)/λ_0` Joules; v0 = Threshold frequency and λ0 = Threshold wavelength
i. According to the question, an electron absorbs the energy of two photons each of frequency v then v' = 2v where v' is the frequency of emitted electron.
Here, `E_("max") = hv - phi_0`
Thus, maximum energy for emitted electrons is `E_("max") = h(2) - phi_0 = 2hv - phi_0`
ii. The probability of absorbing two photons by the same electron is very low. Hence such emissions will be negligible.
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संबंधित प्रश्न
Plot a graph showing the variation of photoelectric current with collector plate potential at a given frequency but for two different intensities I1 and I2, where I2 > I1.
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Using Einstein’s photoelectric equation shows how the cut-off voltage and threshold frequency for a given photosensitive material can be determined with the help of a suitable plot/graph.
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The electric field at a point associated with a light wave is `E = (100 "Vm"^-1) sin [(3.0 xx 10^15 "s"^-1)t] sin [(6.0 xx 10^15 "s"^-1)t]`.If this light falls on a metal surface with a work function of 2.0 eV, what will be the maximum kinetic energy of the photoelectrons?
(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)
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Choose the correct answer from given options
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The minimum energy required to remove an electron is called ______.
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A student performs an experiment on photoelectric effect, using two materials A and B. A plot of Vstop vs ν is given in Figure.
- Which material A or B has a higher work function?
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Comment on whether it is consistent with Einstein’s theory:
Radiation of frequency 1015 Hz is incident on three photosensitive surfaces A, B and C. Following observations are recorded:
Surface A: no photoemission occurs
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Surface C: photo emission occurs and photoelectrons have some kinetic energy.
Using Einstein’s photo-electric equation, explain the three observations.
