Dual Nature of Radiation and Matter

The number of photons per second on an average emitted by the source of monochromatic light of wavelength 600 nm, when it delivers the power of 3.3 10-3 watt will be : (h = 6.6 10-34 J s)

1. 1015
2. 1018
3. 1017
4. 1016

An electromagnetic wave of wavelength ' ' is incident on a photosensitive surface of negligible work function. If 'm' mass is of photoelectron emitted from the surface has de-Broglie wavelength d, then :

1. = ( 2hmc ) d2
2. = ( 2mhc ) d2
3. d = ( 2mch ) 2
4. = ( 2mch ) d2

Light of frequency 1.5 times the threshold frequency is incident on a photosensitive material. What will be the photoelectric current if the frequency is halved and intensity is doubled?

1. four times
2. one-fourth
3. zero
4. doubled

The energy required to break one bond in DNA is 10-20 J. This value in eV is nearly :

1. 0.6
2. 0.06
3. 0.006
4. 6

An electron is accelerated from rest through a potential difference of V volt. If the de-Broglie wavelength of the electron is 1.227 10-2 nm, the potential difference is :

1. 102 V
2. 103 V
3. 104 V
4. 10 V

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