Question 1.
De-Broglie equation states the:
(a) dual nature
(b) particle nature
(c) wave nature
(d) none of these

Answer

Answer: (a) dual nature

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Question 2.
Protons and alpha particles have the same de-Broglie wavelength. What is same for both of them ?
(a) Energy
(b) Time period
(c) Frequency
(d) Momentum

Answer

Answer: (d) Momentum

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Question 3.
Kinetic energy of emitted electrons depends upon :
(a) frequency
(b) intensity
(c) nature of atmosphere surrounding the electrons
(d) none of these

Answer

Answer: (a) frequency

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Question 4.
De-Broglie wavelength of a body of mass m and kinetic energy E is given by (symbols have their usual meanings):
(a) \(\frac{h}{\sqrt{2mE}}\)
(b) \(\frac{h}{2mE}\)
(c) \(\frac{\sqrt{2mE}}{h}\)
(d) \(\frac{h}{mE}\)

Answer

Answer: (a) \(\frac{h}{\sqrt{2mE}}\)

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Question 5.
The ratio of specific charge of an alpha particle to the proton is:
(a) 1 : 2
(b) 2 : 1
(c) 4 : 1
(d) 1 : 4

Answer

Answer: (a) 1 : 2

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Question 6.
In Thomson’s experiment number of parabola gives :
(a) the no. of electrons present in element
(b) the no. of proton present in element
(c) the no. of neutrons present in element
(d) the no. of isotopes of the element present

Answer

Answer: (d) the no. of isotopes of the element present

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Question 7.
The work function of photoelectric material is 3.3 eV. The threshold frequency will be equal to:
(a) 8 × 10¹⁴ Hz
(b) 8 × 10¹⁰ Hz
(c) 5 × 10¹⁰ Hz
(d) 4 × 10¹⁴ Hz

Answer

Answer: (a) 8 × 10¹⁴ Hz

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Question 8.
The strength of photoelectric current depends upon :
(a) angle of incident radiation
(b) frequency of incident radiation
(c) intensity of incident radiation
(d) distance between anode and cathode

Answer

Answer: (b) frequency of incident radiation

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Question 9.
The momentum of an electron that emits a wavelength of 2 Å. will be:
(a) 6.4 × 10^-36 kgms^-1
(b) 3.3 × 10^-24 kgms^-1
(c) 3.3 × 10^-34 kgms^-1
(d) none of these

Answer

Answer: (b) 3.3 × 10^-24 kgms^-1

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Question 10.
Name the scientists who first studied the passage of electricity through fluids to establish the electrical nature of matter:
(a)Millikan
(b) Planck
(c) Faraday
(d) Boyle

Answer

Answer: (c) Faraday

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Question 11.
Millikan’s oil drop experiment makes use of:
(a) Stokes’ law
(b) Boyle’s law
(c) Gas equation
(d) Bernoulli’s theorem

Answer

Answer: (a) Stokes’ law

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Question 12.
X-rays are:
(a) deflected by an electric field
(b) deflected by a magnetic field
(c) deflected by both electric and magnetic fields
(d) not deflected by electric and magnetic fields

Answer

Answer: (d) not deflected by electric and magnetic fields

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Question 13.
In photo electric emission, for alkali metals the threshold frequency lies in the:
(a) visible region
(b) ultraviolet region
(c) infrared region
(d) far end of the infrared region

Answer

Answer: (a) visible region

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Question 14.
Which of the following radiations cannot eject photo electrons?
(a) ultraviolet
(b) infrared
(c) visible
(d) X-rays

Answer

Answer: (b) infrared

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Question 15.
What is the de-Broglie wavelength of an electron accelerated from rest through a potential difference of V volts?
(a) \(\frac{12.3}{V^2}\) Å
(b) \(\frac{12.3}{V}\) Å
(c) \(\frac{12.2}{V^2}\) Å
(d) None of these

Answer

Answer: (a) \(\frac{12.3}{V^2}\) Å

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Question 16.
What is the de-Broglie wavelength of an electron accelerated from rest through a potential difference of 100 volts?
(a) 12.3 Å
(b) 1.23 Å
(c) 0.123 Å
(d) None of these

Answer

Answer: (b) 1.23 Å

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Question 17.
What is the de-Broglie wavelength of a proton accelerated from rest through a potential difference of V volts?
(a) \(\frac{12.3}{√V}\) Å
(b) \(\frac{12.3}{V}\) Å
(c) \(\frac{12.2}{V^2}\) Å
(d) None of these

Answer

Answer: (d) None of these

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Question 18.
When a yellow light is incident on a surface, no electrons are emitted while green light can emit electrons. If the red light is incident on the surface then:
(a) no electrons are emitted
(b) photons are emitted
(c) electrons of higher energy are emitted
(d) electrons of lower energy are emitted

Answer

Answer: (a) no electrons are emitted

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Question 19.
The de-Broglie wavelength of particle of mass 1 mg moving with a velocity of 1 ms^-1, in terms of Planck’s constant h, is given by (in metre):
(a) 10⁵ h
(b) 10⁶ h
(c) 10^-3 h
(d) 10³ h

Answer

Answer: (b) 10⁶ h

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Question 20.
Evidence of the wave nature of light cannot be obtained from:
(a) diffraction
(b) interference
(c) doppler effect
(d) reflection

Answer

Answer: (d) reflection

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Question 21.
which Characteristic of a target does the Mosley’s law relate the frequency of X-rays?
(a) density
(b) atomic number
(c) atomic weight
(d) interatomic space

Answer

Answer: (b) atomic number

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Question 22.
The charge of a photo electron is :
(a) 9.1 × 10^-31 C
(b) 9.1 × 10^-27 C
(c) 9.1 × 10^-24 C
(d) none of these

Answer

Answer: (d) none of these

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Question 23.
The number of photons of frequency n present in energy E, in terms of Planck’s constant h:
(a) \(\frac{E}{nh}\)
(b) nhE
(c) \(\frac{nh}{E}\)
(d) \(\frac{nE}{h}\)

Answer

Answer: (a) \(\frac{E}{nh}\)

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Question 24.
Compared to liquids and solids, gases are:
(a) good conductors of electricity
(b) best conductors of electricity
(c) very poor conductors of electricity
(d) good or bad conductors of electricity depending upon the nature of the gas

Answer

Answer: (c) very poor conductors of electricity

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Question 25.
The different stages of discharge in a discharge tube can be explained on the basis of:
(a) the wave nature of light
(b) the dual nature of light
(c) wave nature of electrons
(d) the collision between the charged particles emitted from the cathode the atoms of the gas in the tube

Answer

Answer: (d) the collision between the charged particles emitted from the cathode the atoms of the gas in the tube

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Question 26.
When an electron jumps across a potential difference of 1 V, it gains energy equal to :
(a) 1.602 × 10^-19 J
(b) 1.602 × 10¹⁹ J
(c) 1.602 × 10²⁴ J
(d) 1 J

Answer

Answer: (a) 1.602 × 10^-19 J

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