Advertisements
Advertisements
प्रश्न
Consider the situation of the previous problem. Consider the faster electron emitted parallel to the large metal plate. Find the displacement of this electron parallel to its initial velocity before it strikes the large metal plate.
(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)
Advertisements
उत्तर
Electric field of the metal plate,
`E = σ/∈_0 = (1 xx 10^-9)/(8.85 xx 10^-12)`
= 113 V/m
Acceleration,
`a = (qE)/m`,
where q=charge on electron
E=electric field
m=mass of electron
`a = (1.6 xx 10^-19 xx 113)/(9.1 xx 10^-31) = 19.87 xx 10^12`
`t = sqrt((2y)/a) = sqrt((2 xx 20 xx 10^-2)/(19.87 xx 10^12)`
=`1.41 xx 10^-7` s
From Einstein's photoelectric equation,
`K.E. = (hc)/lambda - W = 1.2 "eV"`
= `1.2 xx 1.6 xx 10^-19 "J"...........[because "in problem " 31 : "KE" = 1.2 "eV"`]
`therefore "Velocity", v = sqrt({2KE)/m)`
`= sqrt((2 xx 1.2 xx 1.6 xx 10^-19)/(4.1 xx 10^-31))` `sqrt((2 xx 1.2 xx 1.6 xx 10^-19)/(4.1 xx 10^-31))`
`= 0.665 xx 10^-6 "m/s"`
∴ Horizontal displacement,
`S = v xx t`
`S = 0.665 xx 10^-6 xx 1.4 xx 10^-7`
`S = 0.092 "m" = 9.2 "cm"`
APPEARS IN
संबंधित प्रश्न
In an experiment on the photoelectric effect, the slope of the cut-off voltage versus the frequency of incident light is found to be 4.12 × 10−15 Vs. Calculate the value of Planck’s constant.
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.
Write Einstein’s photoelectric equation?
point out any two characteristic properties of photons on which Einstein’s photoelectric equation is based ?
A monochromatic light source of intensity 5 mW emits 8 × 1015 photons per second. This light ejects photoelectrons from a metal surface. The stopping potential for this setup is 2.0 V. Calculate the work function of the metal.
(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)
Use Einstein’s photoelectric equation to show how from this graph,
(i) Threshold frequency, and (ii) Planck’s constant can be determined.
How does one explain the emission of electrons from a photosensitive surface with the help of Einstein’s photoelectric equation?
Use Einstein's photoelectric equation to show how from this graph,
(i) Threshold frequency, and
(ii) Planck's constant can be determined.
Choose the correct answer from given options
Photons of frequency v are incident on the surface of two metals A and B of threshold frequency 3/4 v and 2/3 v, respectively. The ratio of maximum kinetic energy of electrons emitted from A to that from B is
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 ______.
Each photon has the same speed but different ______.
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?
There are materials which absorb photons of shorter wavelength and emit photons of longer wavelength. Can there be stable substances which absorb photons of larger wavelength and emit light of shorter wavelength.
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?
- Given the electric charge of an electron = 1.6 × 10–19 C, find the value of h obtained from the experiment for both A and B.
Comment on whether it is consistent with Einstein’s theory:
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.
