Advertisements
Advertisements
Question
Write Einstein’s photoelectric equation?
Solution
Einstein’s photoelectric effect equation:
(NOTE: Use any one of three given equations)
hv = φ0 + K.E
where, h = Planck's constant, v = frequency of the incomig photons
φ0 = work function of the material and K.E = kinetic energy of the emitted electrons
or
`hv = phi_0 + 1/2 mv_max^2 `=
where,h = Planck's constant,v = frequency of the incoming photons
φo = work function of the material, 1/2 mv_max^2`kinetic energy of the emitted electrons
Vmax = maximum velocity of emitted electron
or
`1/2 mv_max^2 = h(v - v_o)`
where h = Planck's constant, v = frequency of the incoming photons
vo = threshold frequency, `1/2 mv_max^2= ` kinetic energy of the emitted electrons
vmax = maximum velocity of emitted electron
APPEARS IN
RELATED QUESTIONS
In an accelerator experiment on high-energy collisions of electrons with positrons, a certain event is interpreted as annihilation of an electron-positron pair of total energy 10.2 BeV into two γ-rays of equal energy. What is the wavelength associated with each γ-ray? (1BeV = 109 eV)
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.
Define the terms (i) ‘cut-off voltage’ and (ii) ‘threshold frequency’ in relation to the phenomenon of photoelectric effect.
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.
According to Einstein's photoelectric equation, the plot of the kinetic energy of the emitted photoelectrons from a metal versus the frequency of the incident radiation gives a straight line, whose slope ______.
The minimum energy required to remove an electron is called ______.
The wavelength of a photon needed to remove a proton from a nucleus which is bound to the nucleus with 1 MeV energy is nearly ______.
- 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?
Radiation of frequency 1015 Hz is incident on three photosensitive surfaces A, B and C. Following observations are recorded:
Surface A: no photoemission occurs
Surface B: photoemission occurs but the photoelectrons have zero kinetic energy.
Surface C: photo emission occurs and photoelectrons have some kinetic energy.
Using Einstein’s photo-electric equation, explain the three observations.
A photon of wavelength 663 nm is incident on a metal surface. The work function of the metal is 1.50 eV. The maximum kinetic energy of the emitted photoelectrons is ______.
The photon emitted during the de-excitation from the first excited level to the ground state of a hydrogen atom is used to irradiate a photocathode in which the stopping potential is 5 V. Calculate the work function of the cathode used.
