Dual Nature of Radiation and Matter · Question 22

An electron is accelerated through a potential difference of 10,000 V. Its de Broglie wavelength is (nearly) : (me = 9 10-31 kg)

1. 12.2 10-12 m
2. 12.2 10-13 m
3. 12.2 10-14 m
4. 12.2 nm

An electron of mass m with an initial velocity v = v0 i (v0 > 0) enters an electric field E = -E0 i (E0 = constant > 0) at t = 0. If 0 is its de-Broglie wavelength initially, then its de-Broglie wavelength at time t is

1. 0 (1 + eE0mv0t )
2. 0 (1 + eE0mv0t )
3. 0t
4. 0

When the light of frequency 2 0 (where 0 is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is v1. When the frequency of the incident radiation is increased to 5 0, the maximum velocity of electrons emitted from the same plate is v2. The ratio of v1 to v2 is

1. 1 : 2
2. 1 : 4
3. 4 : 1
4. 2 : 1

The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (kelvin) and mass m, is

1. h 3mkT
2. 2h 3mkT
3. 2h mkT
4. h mkT

The photoelectric threshold wavelength of silver is 3250 10-10 m. The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength 2536 10-10 m is [Given h = 4.14 10-15 eV s and c = 3 108 m s-1]

1. 0.6 106 m s-1
2. 61 103 m s-1
3. 0.3 106 m s-1
4. 6 105 m s-1

An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is

1. c(2mE) 12
2. 1c ( 2mE ) 12
3. 1c ( E2m ) 12
4. ( E2m ) 12

When a metallic surface is illuminated with radiation of wavelength , the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2 , the stopping potential is V4. The threshold wavelength for the metallic surface is

1. 52
2. 3
3. 4
4. 5

Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is

1. +3 V
2. +4 V
3. -1 V
4. -3 V

A photoelectric surface is illuminated successively by monochromatic light of wavelength and /2. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is (h = Planck's constant, c = speed of light)

1. 2hc
2. hc3
3. hc2
4. hc

Light of wavelength 500 nm is incident on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is

1. 2.8 10-9 m
2. 2.8 10-12 m
3. < 2.8 10-10 m
4. < 2.8 10-9 m