Dual Nature of Radiation and Matter  MCQs

MCQs of Dual Nature of Radiation and Matter

Showing 141 to 150 out of 186 Questions
12 13 14 15 16 17
141.
What will be the number of photons emitted per second by a 10 watt sodium vapour lamp assuming that 90% of the consumed energy is converted into light? Wavelength of sodium light is 590 nm. (h= 6.63×10-34 Js)
(a) 0.267×1018
(b) 2.67×1019
(c) 0.267×1020
(d) 0.267×1019
Answer:

Option (b)

142.
A parallel beam of light is incident normally on a plane surface absorbing 40% the light and reflecting the rest. If the incident beam carries 60 W of power, the force exerted by it on the surface is _____ N.
(a) 3.2×10-8
(b) 3.2×10-7
(c) 5.12×10-7
(d) 5.12×10-8
Answer:

Option (b)

143.
A ratio transmitter operates at a frequency of 880 kHz and a power of 10 kW. The number of photons emitted per second is _____ .
(a) 1.72×1031
(b) 1.327×1025
(c) 1.327×1037
(d) 1.327×1045
Answer:

Option (a)

144.
A television center transmits 10 kW power at 150 MHz. The energy of one photon of the electromagnetic wave is nearly _____ .
(a) 6×10-7 eV
(b) 6×107 eV
(c) 6×10-7 J
(d) 6×107 J
Answer:

Option (a)

145.
The photoelectric threshold wavelength of tungsten is 2300 Å. The energy of the electron ejected from the surface by ultraviolet light of wavelength 1800 Å is ______ eV. (h= 6.63×10-34 Js )
(a) 0.15
(b) 1.5
(c) 15
(d) 150
Answer:

Option (b)

146.
A light of wavelength 4000 Å is allowed to fall on a metal surface having work function 2 eV. The maximum velocity of the emitted electron is _____ ms-1. (h= 6.63×10-34 Js)
(a) 1.35×105
(b) 2.7×105
(c) 6.2×105
(d) 8.1×105
Answer:

Option (c)

147.
The work function of a metal surface is 4.2 eV.The maximum wavelength which can eject photo electron from this surface is _____ Å .
(a) 2956
(b) 3076
(c) 4116
(d) 5088
Answer:

Option (a)

148.
Radiation of two photons of energy, twice and ten times the work function of metal are incident on the metal surface successively. The ratio of maximum velocities photo-electron emitted in two cases is _____ .
(a) 1:2
(b) 1:3
(c) 1:4
(d) 1:1
Answer:

Option (b)

149.
For a certain metal f=2f0 and electron come out with a maximum velocity of 4×106 ms-1 . If the value of f=5f0, then maximum velocity of photo-electrons will be _____ ms-1 .
(a) 2×106
(b) 4×107
(c) 8×105
(d) 8×106
Answer:

Option (d)

150.
Light of wavelength 4000Å is incident on a metal plate whoes work function is 2 eV. The maximum K.E. of emitted photo-electron will be _____ eV.
(a) 0.5
(b) 1.1
(c) 1.55
(d) 20
Answer:

Option (b)

Showing 141 to 150 out of 186 Questions
12 13 14 15 16 17