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
A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3 × 106 ms-1 . The velocity of the particle is (mass of electron = 9.1 × 10-31 kg)
2.7 × 10-18 ms-1
9 × 10-2 ms-1
3 × 10-31 ms-1
2.7 × 10-21 ms-1
The momentum of a photon of an electromagnetic radiation is 3.3 × 10-29 kg-ms-1 . What is the frequency of the associated waves ?
(h = 6.6 × 10-34 J-s, c = 3 × 108 ms-1 )
1.5 ×1013 Hz
7.5 ×1012 Hz
6.0 ×1013 Hz
3.0 ×103 Hz
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
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
In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential V and then made to describe semicircular paths of radius R using a magnetic field B. If V and B are kept constant, the ratio will be proportional to
R2
R
Monochromatic light of frequency 6.0×1014 Hz is produced by a laser. The power emitted is 2× 10-3 W. The number of photons emitted on the average by the source per second is
5 × 1015
5 × 1016
5 × 1017
5 × 1014
Which of the following is true ?
The stopping potential increases with increasing intensity of incident light
The photo current increases with increasing intensity of light
The current in photocell increases with increasing frequency of light
The photo current is proportional to applied voltage
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 radio transmitter operates at a frequency 880 KHz and a power of 10 kW. The number of photons emitted per second is
1.72 × 1031
1.327 × 1025
1.327 × 1037
1.327 × 1045
