Dual Nature of Radiation and Matter · Question 54

The electron in the hydrogen atom jumps from excited state (n = 3) to its ground state (n = 1) and the photons thus emitted irradiate a photosensitive material. If the work function of the material is 5.1 eV, the stopping potential is estimated to be (the energy of the electron in nth state En = - 13.6n2 eV)

1. 5.1 V
2. 12.1 V
3. 17.2 V
4. 7 V

A source S1 is producing 1015 photons per second of wavelength 5000 A. Another source S2 is producing 1.02 1015 photons per second of wavelength 5100 A. Then, (power of S2)/(power of S1) is equal to

1. 1.00
2. 1.02
3. 1.04
4. 0.98

The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200 nm falls on it, must be

1. 2.4 V
2. -1.2 V
3. -2.4 V
4. 1.2 V

The number of photo electrons emitted for light of a frequency (higher than the threshold frequency 0) is proportional to

1. threshold frequency ( 0)
2. intensity of light
3. frequency of light ( )
4. - 0

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? [figure]

1. Curves (a) and (b) represent incident radiations of same frequency but of different intensities.
2. Curves (b) and (c) represent incident radiations of different frequencies and different intensities.
3. Curves (b) and (c) represent incident radiations of same frequency having same intensity.
4. Curves (a) and (b) represent incident radiations of different frequencies and different intensities.

Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per sec. on the average at a target irradiated by this beam is

1. 3 1016
2. 9 1015
3. 3 1019
4. 9 1017

The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the

1. infrared region
2. X-ray region
3. Ultraviolet region
4. Visible region

A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3 106 m s-1. The velocity of the particle is

1. 3 10-31 m s-1
2. 2.7 10-21 m s-1
3. 2.7 10-18 m s-1
4. 9 10-2 m s-1

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

1. 5 1016
2. 5 1017
3. 5 1014
4. 5 1015

A 5 watt source emits monochromatic light of wavelength 5000 A. 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

1. 8
2. 16
3. 2
4. 4