The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement ?
Curves a and b represent incident radiations of different frequencies and different intensities
Curves a and b represent incident radiations of same frequency but of different intensities
Curves b and c represent incident radiations of different frequencies and different intensities
Curves b and c represent incident radiations of same frequency having same intensity
A photosensitive metallic surface has work function, hv0. If photons of energy 2 hv0 fall on this surface, the electrons come out with a maximum velocity of 4 × 106 m/s. When the photon energy is increased to 5 hv0, then maximum velocity of photoelectrons will be
2 × 106 m/s
2 × 107 m/s
8 × 105 m/s
8 × 106 m/s
An electron moves with a velocity 1 ×103 m/s in a magnetic field of induction 0.3 T at an angle 30o. If of electron is 1.76 × 1011 C/kg, the radius of the path is nearly
10-8 m
2 × 10-8 m
10-6 m
10-10 m
The energy of a photon of wavelength λ is
hcλ
Gases begin to conduct electricity at low pressure because
at low pressures gases turn to plasma
colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionisation of atoms
atoms break up into electrons and protons
the electrons in atoms can move freely at low pressures
In a photoemissive cell, with exciting wavelength λ, the fastest electron has speed v. If the exciting wavelength is changed to 3λ/4, the speed of the fastest emitted electron will be
less than
greater than
The momentum of a photon of energy 1 MeV in kg m/s, will be
0.33 × 106
7 × 10-24
10-22
5 × 10-22
The number of photoelectrons emitted for light of a frequency v (higher than the threshold frequency v0 ) is proportional to
v - v0
threshold frequency (v0 )
intensity of light
frequency of light (v)
A photocell employs photoelectric effect to convert
change in the frequency of light into a change in electric voltage
change in the intensity of illumination into a change in photoelectric current
change in the intensity of illumination into a change in the work function of the photo cathode
change in the frequency of light into a change in the electric current
According to Einstein's photoelectric equation, the graph between the kinetic energy of photo electrons ejected and the frequency of incident radiation is