CBSE
Multiple Choice Questions20 kV potential is applied across X-ray tube, the minimum wavelength of X-ray emitted will be
0.62 Ao
0.37 Ao
1.62 Ao
1.31 Ao
The work function of sodium is 2.3 eV. The threshold wavelength of sodium will be
2900 Ao
2500 Ao
5380 Ao
1200 Ao
A photocell is illuminated by a small bright source placed 1m away. When the same source of light is placed 2m away, the electrons emitted by photo cathode
Carry one quarter of their previous energy
carry one quarter of their previous momenta
are half as numerous
are one quarter as numerous
The energy in MeV is released due to transformation of 1kg mass completely into energy is (c=3×108 m/s)
7.625×10MeV
10.5×1029MeV
2.8×10-28MeV
5.625×1029MeV
If work function of a metal is 4.2 eV, the cut off wavelength is
8000 Ao
7000 Ao
1472 Ao
2950 Ao
A light of wavelength 2000 Ao falls on a metallic surface of work function 5.01 eV then required potential difference to slope fastest photoelectron is (h = 6.62 x 10-34J-s)
4.8V
3.6V
2.4V
1.2V
The wavelength λ of a photon and the de-Broglie wavelength of an electron have the same value. Find the ratio of the energy of a photon to the kinetic energy of an electron in terms of mass m, the speed of light c and Planck constant.
The enregy of a photon corresponding to the visible light maximum wavelength is nearly
7ev
3.2eV
1eV
1.6eV
A beam of light composed of red and green rays is incident obliquely at a point on the face of a rectangular glass slab. When coming out on the opposite parallel face, the red and green rays emerge from.
Two points propagating in two different non- parallel directions.
Two points propagating in two different parallel directions
one point propagating in two different directions.
one point propagating in the same direction.
An isotropic point source of light is suspended h metre vertically above the centre of the circular table of radius r metre. Then, the ratio of illumenances at the centre to that at the edge of the table is
