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CBSE Questions for Class 12 Medical Physics Dual Nature Of Radiation And Matter Quiz 1 - MCQExams.com

A free particle with initial kinetic energy E and de-broglie wavelength λ enters a region in which it has potential energy U. What is the particle's new de-Broglie wavelength?
  • λ(1U/E)1/2
  • λ(1U/E)
  • λ(1U/E)1
  • λ(1U/E)1/2
In which of the following photocell is not used?
  • Burglar alarm
  • Television camera
  • Automatic street lights
  • Vacuum cleaner
If the KE of a free electron doubles then its de-Broglie wavelength changes by a factor
  • 12
  • 12
  • 2
  • 2
The ratio of the energy of a photon of 2000˚A wavelength  to that of 4000˚A wavelength is :
  • 1/4
  • 4
  • 1/2
  • 2
If a photon has velocity c and frequency v, then which of the following represents its wavelength
  • hcE
  • hvc
  • hvc2
  • hv
The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately: 
  • 540 nm
  • 400 nm
  • 310 nm
  • 220 nm
Photon of frequency v  has a momentum associated with it. If c  is the velocity of light, the momentum is 
  • v/c
  • hvc
  • hv/c2
  • hv/c
A Laser light of wavelength 660nm is used to weld Retina detachment. If a Laser pulse of width 60ms and power 0.5kW is used, the approximate number of photons in the pulse are:
[Take Planck's constant h=6.62×1034Js]
  • 1020
  • 1018
  • 1022
  • 1019
For which of the following particles will it be most difficult to experimentally verify the de-Broglie relationship?
  • An electron
  • A proton
  • An αparticle
  • A dust particle
If electron charge e, electron mass m, speed of light in vacuum c and Planck's constant h are taken as fundamental constant h are taken as fundamental quantities, the permeability of vacuum μ0 can be expressed in units of
  • (mc2he2)
  • (hme2)
  • (hcme2)
  • (hce2)
If the de Broglie wavelengths associated with a proton and an \alpha - particle are equal, then the ratio of velocities of the proton and the \alpha - particle will be:
  • 1:4
  • 1:2
  • 4:1
  • 2:1
De-Broglie wavelength of an electron accelerated by a voltage of 50 V is close to: (|e|=1.6 \times 10^{-19} C, m_e=9.1 \times 10^{-31}kg, h=6.6 \times 10^{-34} Js). 
  • 0.5 \mathring {A}
  • 1.7 \mathring {A}
  • 2.4 \mathring {A}
  • 1.2 \mathring {A}
The de-Broglie wavelength (\lambda_{B}) associated with the electron orbiting in the second excited state of hydrogen atom is related to that in the ground state (\lambda_{G}) by :
  • \lambda_{B} = \lambda_{G}/3
  • \lambda_{B} = \lambda_{G}/2
  • \lambda_{B} = 2\lambda_{G}
  • \lambda_{B} = 3\lambda_{G}
Two electrons are moving with non-relativistic speeds perpendicular to each other. If corresponding de Broglie wavelengths are { \lambda  }_{ 1 } and { \lambda  }_{ 2 }, their de Broglie wavelength in the frame of reference attached to their centre of mass is:
  • { \lambda }_{ CM }={ \lambda }_{ 1 }={ \lambda }_{ 2 }\quad
  • \cfrac { 1 }{ { \lambda }_{ CM } } =\cfrac { 1 }{ { \lambda }_{ 1 } } +\cfrac { 1 }{ { \lambda }_{ 2 } }
  • { \lambda }_{ CM }=\cfrac { 2{ \lambda }_{ 1 }{ \lambda }_{ 2 } }{ \sqrt { { { \lambda }_{ 1 } }^{ 2 }+{ { \lambda }_{ 2 } }^{ 2 } } }
  • { \lambda }_{ CM }=\left( \cfrac { { \lambda }_{ 1 }+{ \lambda }_{ 2 } }{ 2 } \right)
An electron (mass m) with initial velocity \vec { v } ={ v }_{ 0 }\hat { i } +{ v }_{ 0 }\hat { j } is an electric field \vec { E } =-{ E }_{ 0 }\hat { k } . If { \lambda  }_{ 0 } is initial de-Broglie wave length at time t is given by
  • \cfrac { { \lambda }_{ 0 } }{ \sqrt { 1+\cfrac { { e }^{ 2 }{ E }^{ 2 }{ t }^{ 2 } }{ 2{ m }^{ 2 }{ v }_{ 0 }^{ 2 } } } }
  • \cfrac { { \lambda }_{ 0 }\sqrt { 2 } }{ \sqrt { 1+\cfrac { { e }^{ 2 }{ E }^{ 2 }{ t }^{ 2 } }{ { m }^{ 2 }{ v }_{ 0 }^{ 2 } } } }
  • \cfrac { { \lambda }_{ 0 } }{ \sqrt { 2+\cfrac { { e }^{ 2 }{ E }^{ 2 }{ t }^{ 2 } }{ { m }^{ 2 }{ v }_{ 0 }^{ 2 } } } }
  • \cfrac { { \lambda }_{ 0 } }{ \sqrt { 1+\cfrac { { e }^{ 2 }{ E }_{ 0 }^{ 2 }{ t }^{ 2 } }{ { m }^{ 2 }{ v }_{ 0 }^{ 2 } } } }
The allowed energy for the particle for a particular value of n is proportional to :
  • \mathrm{a}^{-2}
  • \mathrm{a}^{-3/2}
  • \mathrm{a}^{-1}
  • \mathrm{a}^{2}
A pulse of light of duration 100 ns is absorbed completely by a small object initially at rest. Power of the pulse is 30mWand the speed of light is 3\times 10^{8}m/s. The final momentum of the object is:
  • 0.3\times 10^{-17}kgms^{-1}
  • 1.0\times 10^{-17}kg ms^{-1}
  • 3.0\times 10^{-17}kgms^{-1}
  • 9.0\times 10^{-17}kgms^{-1}
Emission of photoelectrons will not take place light if two different frequencies, whose photons have energy 1 electron volt and 2.5 electron volt are incident one by one on a metal surface of work function 0.5 electron volt. The ratio of maximum energy of emitted electrons will be ?
  • 1:4
  • 4:1
  • 1:2
  • 2:1
The speed of the particle that can take discrete values is proportional to
  • \mathrm{n}^{-3/2}
  • \mathrm{n}^{-1}
  • \mathrm{n}^{1/2}
  • n
Light of wavelength \displaystyle { \lambda  }_{ ph } falls on a cathode plate inside a vacuum tube as shown in the figure. The work function of the cathode surface is \displaystyle \phi  and the anode is a wire mesh of conducting material kept at a distance d from the cathode. A potential difference V is maintained between the electrodes. If the minimum de Broglie wavelength of the electrons passing through the anode is \displaystyle { \lambda  }_{ e }, which of the following statement(s) is(are) true?
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  • \displaystyle { \lambda }_{ e } increases at the same rate as { \lambda }_{ ph } for \lambda_{ph} < hc / \phi
  • \displaystyle { \lambda }_{ e } is approximately halved, if d is doubled
  • \displaystyle { \lambda }_{ e } decreases with increase in \displaystyle \phi and \displaystyle { \lambda }_{ ph }
  • For large potential difference \displaystyle \left( V>>\phi /e \right) { \lambda }_{ e } is approximately halved if V is made four time
Electrons of mass m with de-Broglie wavelength \lambda fall on the target in an X-rays tube. The cutoff wavelength (\lambda_0) of the emitted X-rays is
  • \lambda_0=\lambda
  • \lambda_0=\dfrac{2mc\lambda^2}{h}
  • \lambda_0=\dfrac{2h}{mc}
  • \lambda_0=\dfrac{2m^2c^2\lambda^3}{h^2}
A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (C= Velocity of light)
  • \frac {2E}{C^2}
  • \frac {E}{C^2}
  • \frac {E}{C}
  • \frac {2E}{C}
Light of wavelength 500\ nm is incident on a metal with a work function 2.28\ eV. The de Borglie wavelength of the emitted electron is:
  • \leq 2.8 \times 10^{-12}m
  • < 2.8 \times 10^{-10}m
  • < 2.8 \times 10^{-9}m
  • \geq 2.8 \times 10^{-9}m
If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de-Broglie wavelength of the particle is :
  • 25
  • 75
  • 60
  • 50
Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?
An electron is accelerated from rest through a potential difference of V volt. If the de Broglie wavelength of the electron is 1.227 \times 10^{-2} nm, the potential difference is :
  • 10^2V
  • 10^3V
  • 10^4V
  • 10V
An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelength associated with them is:
  • \dfrac { 1 }{ c } { \left( \dfrac { E }{ 2m } \right) }^{ \dfrac { 1 }{ 2 } }
  • { \left( \dfrac { E }{ 2m } \right) }^{ \dfrac { 1 }{ 2 } }
  • c{ \left( 2mE \right) }^{ \dfrac { 1 }{ 2 } }
  • \dfrac { 1 }{ c } { \left( \dfrac { 2m }{ E } \right) }^{ \dfrac { 1 }{ 2 } }

    (c being velocity of light)
The wavelength \lambda _{e} of an electron and \lambda _{p} of a photon of same energy E are related by :
  • \lambda _{p}\propto \lambda _{e}^{2}
  • \lambda _{p}\propto \lambda _{e}
  • \lambda _{p}\propto \sqrt{\lambda _{e}}
  • \displaystyle \lambda _{p}\propto \dfrac{1}{\sqrt{\lambda _{e}}}
If the momentum of an electron is changed by P, then the de-Broglie wavelength associated with it changes by 0.5%. The initial momentum of electron will be :
  • 400P
  • \cfrac{P}{200}
  • 100P
  • 200P
If the kinetic energy of a particle is increased by 16 times, the percentage change in the de Broglie wavelength of the particle is:
  • 25%
  • 75%
  • 60%
  • 50%
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Both Assertion and Reason are incorrect
De Broglie wavelength \lambda associated with neutrons is related with absolute temperature T as:
  • \lambda \propto T
  • \lambda \propto \frac{1}{T}
  • \lambda \propto \frac{1}{\sqrt{T}}
  • \lambda \propto T^2
If we assume kinetic energy of a proton is equal to energy of the photon, the ratio of de Broglie wave length of proton to photon is proportional to :
  • \displaystyle E
  • \displaystyle { E }^{ { -1 }/{ 2 } }
  • \displaystyle { E }^{ { 1 }/{ 2 } }
  • \displaystyle { E }^{ { 3 }/{ 2 } }
If velocity of a particle is three times of that of electron and ratio of de Broglie wavelength of particle to that of electron is 1.814 \times 10^{-4}. The particle will be :
  • Neutron
  • Deutron
  • Alpha
  • Tritium
Monochromatic light of wavelength 3000\overset {\circ}{A} is incident on a surface area 4\ cm^{2}. If intensity of light is 150\ mW/m^{2}, then rate at which photons strike the target is
  • 3\times 10^{10}/s
  • 9\times 10^{13}/s
  • 7\times 10^{15}/s
  • 6\times 10^{19}/s
The de Broglie wavelength of a neutron when its kinetic energy is K, is \lambda. What will be its wavelength when its kinetic energy is 4K ?
  • \dfrac{\lambda}{4}
  • \dfrac{\lambda}{2}
  • 2\lambda
  • 4\lambda
The photoelectric threshold energy of certain metal is 3 eV. If light of wavelength 3000 A^{o} is incident on the metal, then :
  • Electrons will be emitted
  • Positrons will be emitted
  • Protons will be emitted
  • Electrons will not be emitted
An electron beam after collision with the target produces X-rays of wavelength 4 A^0. The velocity of the electron beam is
  • 3.31\times 10^{7}m/s
  • 6.31\times 10^{7}m/s
  • 8.31\times 10^{7}m/s
  • 9.31\times 10^{7}m/s
The momentum of a proton is p. The corresponding wavelength is
  • h/p
  • hp
  • p/h
  • \sqrt{hp}
Moving with the same velocity, one of the following has the longest de Broglie wavelength
  • \beta -particle
  • \alpha -particle
  • proton
  • neutron
A photon of frequency {\text{x}} has an energy
  • \dfrac{h}{x^{2}}
  • \dfrac{x}{h}
  • hx
  • hx^{2}
The wavelength of matter waves does not depend on
  • Momentum
  • Velocity
  • Mass
  • Charge
De-Broglie wavelength depends on
  • Mass of the particle
  • Size of the particle
  • Material of the particle
  • Shape of the particle
If the energy and momentum of a photon are E and P respectively, then the velocity of photon will be:
(one or more than one correct)
  • E/P
  • (E/P)^{2}
  • EP
  • 3\times 10^{8}m/s
The effective mass of photon in microwave region, visible region and x -ray region is in the following order:
  • X-rays > Visible > Microwave
  • Microwave > X-rays > Visible
  • X-rays > Microwave > Visible
  • Microwave > Visible> X-ray
Matter waves are:
  • Electromagnetic waves
  • Mechanical waves
  • Either mechanical or electromagnetic waves
  • Neither mechanical nor electromagnetic waves
The frequency of a photon associated with an energy of 3.31 eV is (given h=6.625\times 10^{-34} Js)
  • 0.8\times 10^{15}
  • 1.6\times 10^{15}
  • 3.2\times 10^{15}
  • 8.0\times 10^{15}
A proton when accelerated through a potential difference of  V volt has a wavelength \lambda associated with it. An \alpha  - particle in order to have the same wavelength \lambda  must be accelerated through a p.d. of
  • V/8 volt
  • V/4 volt
  • V volt
  • 2V volt
The wavelength associated with an electron having kinetic energy is given by the expression:
  • h/\sqrt{2mE}
  • 2h/mE
  • 2 mhE
  • \dfrac{2\sqrt{2mE}}{h}
De Broglie wavelength ‘\lambda ’ is proportional to
  • \dfrac{1}{\sqrt{E}} for photons and \dfrac{1}{E} for particles
  • \dfrac{1}{E} for photons and \dfrac{1}{\sqrt{E}} for particles
  • \dfrac{1}{E} for both photons and particles in motion
  • \dfrac{1}{\sqrt{E}} for both photons and particles
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