An ionization chamber with parallel conducting plates as anode and cathode has 5 × 107 electrons and the same number of single charge positive ions per cm3. The electrons are moving towards the anode with velocity 0.4 m/s. The current density from anode to cathode is 4 μ A/m2. The velocity of positive ions moving towards cathode is
0.4 m/s
1.6 m/s
zero
0.1 m/s
If the threshold wavelength for a certain metal is 2000Å, then the work function of the metal is
6.2 J
6.2 eV
6.2 MeV
6.2 keV
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 photocathode
change in the frequency of light into a change in the electric current
A light source is at a distance d from a photoelectric cell, then the number of photoelectrons emitted from the cell is n. If the distance of light source and cell is reduced to half, then the number of photoelectrons emitted will become
2n
4 n
n
In X-rays diffraction experiment distance between atomic lattice planes of diffraction grating is 2.8 ×10-10 m, then the maximum wavelength of X-rays (in metre) is
2.5
5.6 × 10-10
4 × 10-10
4.6 × 10-10
Number of ejected photoelectron increases with increase
in intensity of light
in wavelength of light
in frequency of light
Never
Ultraviolet radiation of 6.2eV falls on an aluminium surface. KE of fastest electron emitted is (work function = 4.2 eV)
3.2 × 10-21 J
3.2 × 10-19 J
7 × 10-25 J
9 × 10-32 J
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)
Light of wavelength 5000Å falls on a sensitive plate with photoelectric work function of 1.9 eV. The kinetic energy of the photoelectron emitted will be
0.58 eV
2.48 eV
1.24 eV
1.16 eV
Photoelectric work function of a metal is 1 eV, light of wavelength λ = 3000Å falls on it. The photoelectrons come out with velocity
10 m/s
102 m/s
104 m/s
106 m/s
