JEE Questions for Physics Dual Nature Of Radiation And Matter Quiz 6 - MCQExams.com

Which of the following devices makes use of the electrons to strike certain substances to produce fluorescence?
  • Thermionic valve
  • Photoelectric cell
  • Cathode ray oscilloscope
  • Electron gun
Output power of He-Ne LASER of low energy is 1.00 mW. Wavelength of the light is 632.8 nm. What will be the number of photons emitted per second from this LASER ?
  • 8.31 × 1015 s–1
  • 5.38 × 1015 s–1
  • 1.83 × 1015 s–1
  • 3.18 × 1015 s–1
A star which can be seen with naked eye from Earth has intensity 1.6 × 10–9 Wm–2 on Earth. If the corresponding wavelength is 560 nm, and the diameter of the human eye is 2.5 × 10–3 m , the number of photons entering in our in 1 s is..............
  • 7.8 × 104 s–1
  • 8.85 × 104 s–1
  • 7.85 × 105 s–1
  • 8.85 × 105 s–1
Find the velocity at which mass of a proton becomes 1.1 times its rest mass, mg = 1.6 × 10–27 kg Also, calculate corresponding temperature. For simplicity, consider a proton as non-interacting ideal-gas particle at 1 atm pressure
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    Physics-Dual Nature of Radiation and Matter-67516.png

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Power produced by a star is 4 × 1028 W . If the average wavelength of the emitted radiations is considered to be 4500 Å the number of photons emitted in 1 s is...............
  • 1 × 1045
  • 9 × 1045
  • 8 × 1045
  • 12 × 1046
Wavelength of light incident on a photo - sensitive surface is reduced form 3500 Å to 290 mm. The change in stopping potential is....... (h = 6.625 × 10–24 J.s)
  • 42.73 × 10–2 V
  • 27.34 × 10–2 V
  • 73.42 × 10–2 V
  • 43.27 × 10–2 V
What should be the ratio of de-Broglie wavelength of an atom of nitrogen gas at 300 K and 1000 K. Mass of nitrogen atom is 4.7 × 1026 Kg and it is at 1 atm pressure Consider it as an ideal gas.
  • 2.861
  • 8.216
  • 6.281
  • 1.826
An electric bulb of 100 W converts 3% of electrical energy into light energy. If the wavelength of light emitted is 6625 Å, the number of photons emitted is 1 s is........ (h = 6.625 × 10–34 J.s)
  • 1017
  • 1019
  • 1021
  • 1015
Work function of Zn is 3.74 eV. If the sphere of Zn is illuminated by the X-ray of wavelength 12 Å the maximum potential produced on the sphere is......... (h = 6.625 × 10–34 J.s)
  • 10.314 V
  • 103.14 V
  • 1031.4 V
  • 10314 V
Consider the radius of a nucleus to be 10–15 m. If an electron is assumed to be in such nucleus, what will be its energy ? (me = 9.1 × 10–3 kg, h = 6.625 × 10–34 J.s )
  • 5.59 × 103
  • 9.55 × 103
  • 5.95 × 103
  • 7.45 × 103
A proton falls freely under gravity of Earth. Its de Broglie wavelength after 10 s of its motion is......., Neglect the forces other than gravitational force.
Physics-Dual Nature of Radiation and Matter-67525.png
  • 3.96 Å
  • 39.6 Å
  • 6.93 Å
  • 69.3 Å
Compare energy of a photon of X-rays having 1Å wavelength with the energy of an electron having same de Broglie wavelength. (h = 6.625 × 10–34 J.s, c = 108 ms–1 , 1eV = 1.6 × 10–19 J)
  • 8.24
  • 2.48
  • 82.4
  • 24.8
An electron is at a distance of 10 m form a charge of 10 C. Its total energy is 15.6 × 10–10 J . Its de - Broglie wavelength at this point is...................
(h = 6.625 × 10–34 J.s, me = 9.1 × 10–31 kg, k = 9 × 109 SI)
  • 9.87 Å
  • 9.87 Fermi
  • 8.97 Å
  • 8.97 Fermi

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    Physics-Dual Nature of Radiation and Matter-67529.png

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As shown in the figure, light of energy P (joule) is incident on a small, flat strip of metal of mass m, suspended with the help of weightless string of length l in 1s. All the energy incident on it is absorbed and the strip remains in equilibrium at an angle θ with respect to vertical. If the light is monochromatic, angle θ is................
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    Physics-Dual Nature of Radiation and Matter-67535.png

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U. V. light of wavelength 200 mm is incident on polished surface of Fe. work function of the surface is 4.5 eV. Find maximum speed of photo electrons.
(h = 6.625 × 10–34 J.s, c = 3 × 108 ms–1. 1 eV = 1.6 × 10–19)
  • 7.75 × 104 m/s
  • 875 × 105 m/s
  • 8.75 × 104 m/s
  • 7.75 × 105 m/s
Light of 4560 Å 1 mW is incident on photo-sensitive surface of Cs (Cesium). If the quantum efficiency of the surface is 0.5% what is the amount of photoelectric current produced ?
  • 1.84 mA
  • 4.18 µA
  • 4.18 mA
  • 1.84 µA
Work function of metal is 2 eV. Light of intensity 10–5 Wm–2 is incident on 2 cm2 area of it. If 1017 electrons of these metals absorb the light, in how much time does the photo electric effect start ? Consider the waveform of incident light
  • 1.4 × 107 s
  • 1.5 × 107 s
  • 1.6 × 107 s
  • 1.7 × 107 s
Radius of a beam of radiation of wavelength 5000 Å is 10–3 m . Power of the beam is 10–3 W . This beam is normally incident on a metal of work function 1.9 eV. The charge emitted by the metal per unit area in unit time is...............Assume that each incident photon emits one electron.
(h = 6.625 × 10–34 J.s)
  • 1.282 C
  • 12.82 C
  • 128.2 C
  • 1282 C
11 × 1011 Photons are incident on a surface in 10 s. These photons correspond to a wavelength of 10 Å . If the surface area of the given surface is 0.01 m2, the intensity of given radiations is...........
(h = 6.625 × 10–34 J.s)
  • 21.86 × 10–3 W/m2
  • 2.186 × 10–3 W/m2
  • 218.6 × 10–3 W/m2
  • 2186 × 10–3 W/m2
If alpha particle and neutron move with velocity v and 2v, the ratio of their de-Brogle wavelength will be.....................
  • 1 : √2
  • 2 : 1
  • 1 : 1
  • √2 : 1
Uncertainty in position of electron is found of the order of de-Broglie wavelength. Using Heisenberg\'s uncertainty principle, it is found that order of uncertainty in its velocity = ............
  • 1v
  • 2v
  • v/2π
  • 2πv
Frequency of incident light on body is f. Threshold frequency of body is f0 . Maximum velocity of electron = ..................where m is mass of electron.

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If electron is accelerated under 50 KV in microscope, find its de-Broglie wavelength.
  • 5.485 × 10–12 m
  • 8.545 × 10–12 m
  • 4.585 × 10–12 m
  • 5.845× 10–12 m
Energy of photon having wavelength is 2 eV. Maximum velocity of emitted photo electron after incidence of photon is v. If value of is decreased by 25% and maximum velocity is made double, work function metal will be.................eV
  • 1.2
  • 1.5
  • 1.6
  • 1.8
Energy of photon of light having two different frequencies are 2 eV and 10 eV respectively. If both are incident on the metal having work function 1 eV, ratio of maximum velocities of emitted electron is.................
  • 1 : 5
  • 3 : 11
  • 2 : 9
  • 1 : 3
What will be velocity of particle having mass 3 times the rest mass ? (c = 3 × 108 m/s)
  • 1.83 × 108 m/s
  • 0.92 × 108 m/s
  • 2.83 × 108 m/s
  • 5.66 × 108 m/s
De-Broglie wavelength of particle moving at a 1/4 th of speed of light having rest mass m0 is.........

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An oxide coated filament is useful in vacuum tubes because essentially
  • It has high melting point
  • It can with stand high temperatures
  • It has good mechanical strength
  • It can emit electrons at relatively lower temperatures
Work function of metal is 2.5 eV. If wave length of light incident on metal plate is 3000 Å , stopping potential of emitted electron will be.............
  • 0.82 v
  • 0.41 v
  • 1.64 v
  • 3.28 v
An electron enters perpendicularly into uniform magnetic field having magnitude 0.5 × 10–4 T . If it moves on a circular path of radius 2 mm, its de - Broglie wavelength is ......... Å
  • 3410
  • 4140
  • 2070
  • 2785
In photoelectric effect, work function of mateal is 3.5 eV. By applying - 1.2V potential, photo electric current becomes zero, so..........
  • energy of incident photon is 4.7 eV.
  • energy of incident photon is 2.3 eV
  • If photon having higher frequency is used, photo electric current is produced.
  • When energy of photon is 2.3 eV, photo electric current becomes maximum
Work function of tungsten and sodium are 4.5 eV and 2.3 eV respectively. If threshold wavelength for sodium is 5460 A, threshold frequnecy for tungsten will be................
  • 1015 Hz
  • 1.1 × 1015 Hz
  • 1.2 × 1015 Hz
  • 1.4 × 1015 Hz
Ration of momentum of photons having wavelength 4000 Å & 8000 Å is..............
  • 2 : 1
  • 1 : 2
  • 20 : 1
  • 1 : 20
Work function of metal is 4.2 eV. If ultraviolet radiation (photon) having energy 6.2 eV, stopping potential will be..................
  • 2 eV
  • 2 V
  • 4.0V
  • 10.4 eV
If intensity of incident light is increased,.........of photo electrons will increase.
  • number
  • Frequency
  • energy
  • wavelength
A photon having energy 5.5 eV is incident on metal surface and emits photo electrons having maximum kinetic energy 0.4 eV. Then stopping potential of this electron is..................
  • 5.5 eV
  • 5.1 eV
  • 5.9 eV
  • 4.0 eV
Frequency of photon having energy 66 eV is............ (h = 6.625 × 10–34 J.s)
  • 8 × 10–15 Hz
  • 12 × 10–15 Hz
  • 16 × 10–15 Hz
  • 24 × 10–15 Hz
Kinetic energy of proton accelerated under p.d. 1 V will be................
  • 1840 eV
  • 13.6 eV
  • 1 eV
  • 0.54 eV
Which of the following phenomenon can not be explained by quantum theory of light ?
  • Emission of radiation from black body
  • Photo electric effect
  • Polarisation
  • Crompton effect
What will be velocity of light of particle having mass double than its rest mass ?

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    Physics-Dual Nature of Radiation and Matter-67559.png

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If de-Broglie wavelength of electron is increased by 1 % its momentum................
  • increases by 1%
  • decreases by 1%
  • increased by 2%
  • decreases by 2%
With how much p.d. should an electron be accelerated, so that its de-Broglie wavelength is 0.4 Å
  • 9410 V
  • 94.10 V
  • 9.140 V
  • 941.0 V
de-Broglie wavelength of atom at T K absolute temperature will be....................

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    Physics-Dual Nature of Radiation and Matter-67566.png

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Uncertainty of momentum of particle is 10–30 kg ms–1 so minimum uncertainty in its position is.........m.
  • 10–8 m
  • 10–12 m
  • 10–16 m
  • 10–4 m
An electron is accelerated between two points having potential 20 V and 40 V, de- Broglic wavelength of electron is..................
  • 0.75 Å
  • 7.5 Å
  • 2.75 Å
  • 0.75 nm
de - Broglic wavelength of electron in nth Bohr orbit is............

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If work function of potassium is 3 eV. its threshold wavelength = ..................
(h = 6.625 × 10–34 J.s, c = 3 × 108 ms–1. 1 eV = 1.6 × 10–19 J.s)
  • 4125 Å
  • 1860 Å
  • 1860 nm
  • 4125 nm
In photo electric effect, if threshold wave length of a metal is 5000 Å work function of this metal is....................eV.
(h = 6.625 × 10–34 J.s, c = 3 × 108 ms–1. 1 eV = 1.6 × 10–19 J.s)
  • 1.24
  • 2.48
  • 4.96
  • 3.72
Work functions for tungsten and sodium are 4.5 eV and 2.3 eV respectively. If threshold wavelength of sodium is 5460 Å , threshold wavelength for tungsten will be......................Å 
  • 528
  • 10683
  • 2791
  • 5893
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