A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m, then
each emitted electron carries half the initial energy
number of electrons emitted is a quarter of the initial number
each emitted electron carries one quarter of the initial energy
number of electrons emitted is half the initial number
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
Doubly ionised helium atoms and hydrogen ions are accelerated from rest through the same potential drop. The ratio of the final velocities of the helium and the hydrogen ion is
2
The wavelength associated with an electron, accelerated through a potential difference of 100 V, is of the order of
1000 Å
100 Å
10.5 Å
1.2 Å
The nature of ions knocked out from hot surfaces is
protons
electrons
neutrons
nuclei
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 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 photoelectric effect, the work function of a metal is 3.5 eV. The emitted electrons can be stopped by applying a potential of - 1.2 V. Then
the energy of the incident photons is 4.7 eV
the energy of the incident photons is 2.3 eV.
if higher frequency photons be used, the photoelectric current will rise
when the energy of photos is 3.5 eV, the photoelectric current will be maximum
The energy of a photon of light is 3 eV. Then the wavelength of photon must be
4125 nm
412.5 nm
41250 nm
4 nm
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
