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
The energy of a photon of wavelength λ is
hcλ
Kinetic energy of an electron which is accelerated in a potential difference of 100 V is
1.6 × 10-17 J
1.6 × 10-19 J
1.6 × 10-21 J
1.6 × 10-25 J
When ultraviolet rays are incident on metal plate, the photoelectric effect does not occur. It occurs by incidence of
infrared rays
X-rays
radiowaves
light waves
The work functions for metals A,B and C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein's equation, the metals which will emit photoelectrons for a radiation of wavelength 4100Å is/are
None
A only
A and B only
All the three metals
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
Which of the following is not the property of cathode rays ?
It produces heating effect
It does not deflect in electric field
Its casts shadow
It produces fluorescence
A 5 W source emits monochromatic light of wavelength 5000Å. When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0 m, the number of photoelectrons liberated will be reduced by a factor of
4
8
16
2
Einstein's work on photoelectric effect gives support to
E = mc2
E = hv
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
