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CBSE Questions for Class 12 Medical Physics Dual Nature Of Radiation And Matter Quiz 5 - MCQExams.com

The energy E and the momentum p of a photon is given by E=hv and p= hλ. The velocity of photon will be 
  • E/p
  • Ep
  • (E/P)2
  • E/P
103W of 5000oA light is directed on a photoelectric cell. If the current in the cell is 0.16μA, the percentage of incident photons which produce photoelectrons, is
  • 40%
  • 0.04%
  • 20%
  • 10%
If 5% of the energy supplied to a bulb is irradiated as visible light, how many quanta are emitted per second by a 100 W lamp? Assume wavelength of visible light of 5.6\times 10^{-5} cm.
  • 1.4\times 10^{19}
  • 3\times 10^{3}
  • 1.4\times 10^{-19}
  • 3\times 10^{4}
The radius of the second orbit of an electron in hydrogen atom is 2.116\overset {o}{A}. The de Broglie wavelength associated with this electron in this orbit would be
  • 6.64\overset {o}{A}
  • 1.058\overset {o}{A}
  • 2.116\overset {o}{A}
  • 13.28\overset {o}{A}
If \lambda_1 and \lambda_2 denote the wavelengths of de Broglie waves for electrons in the first and second Bohr orbits in a hydrogen atom, then \lambda_1/\lambda_2 is equal to :
  • 2
  • \dfrac{1}{2}
  • \dfrac{1}{4}
  • 4
A particle of mass M at rest decays into two masses m_1 and m_2 with non-zero velocities. The ratio \lambda_1 / \lambda_2 of de Broglie wavelengths of particles is
  • m_2/m_1
  • m_1/m_2
  • \sqrt {m_1}/\sqrt {m_2}
  • 1:1
A particle of mass m is projected from ground with velocity u making angle \theta with the vertical. The de Broglie wavelength of the particle at the highest point is
  • \infty
  • h/mu sin\theta
  • h/mu cos\theta
  • h/mu
What is the wavelength of a photon of energy 1eV?
  • 12.4\times 10^3\overset {o}{A}
  • 2.4\times 10^3\overset {o}{A}
  • 0.4\times 10^2\overset {o}{A}
  • 1000\overset {o}{A}
How many photons of a radiation of wavelength \lambda=5\times 10^{-7} m must fall per second on a blackened plate in order to produce a force of 6.62\times 10^{-5}N?
  • 3\times 10^{19}
  • 5\times 10^{22}
  • 2\times 10^{22}
  • 1.67\times 10^{18}
A particle of mass 3m at rest decays into two particles of masses m and 2m having non-zero velocities. The ratio of the de Broglie wavelengths of the particles (\lambda_1/\lambda_2) is
  • 1/2
  • 1/4
  • 2
  • None of these
How many photons are emitted per second by a 5 mW laser source operating at 632.8 nm?
  • 1.6\times 10^{16}
  • 1.6\times 10^{13}
  • 1.6\times 10^{10}
  • 1.6\times 10^{3}
The de Broglie wavelength of a thermal neutron at 927^oC is \lambda. Its wavelength at 327^oC will be
  • \lambda /2
  • \lambda /\sqrt 2
  • \lambda \sqrt 2
  • 2\lambda
The energy of a photon is equal to the kinetic energy of a proton. The energy of photon is E. Let \lambda_1 be the de Broglie wavelength of the proton and \lambda_2 be the wavelength of the photon. Then, \lambda_1/\lambda_2 is proportional to :
  • E^0
  • E^{1/2}
  • E^{-1}
  • E^{-2}
A helium-neon laser has a power output of 1 mW of light of wavelength 632.8 nm. Calculate the energy of each photon in eV.
  • 2.5
  • 1.96
  • 0.53
  • 3.3
Two hydrogen atoms are in excited state with electrons residing in n=2. The first one is moving toward left and emits a photon of energy E_1 toward right. The second one is moving toward right with the same speed and emits a photon of energy E_2 toward left. Taking recoil of nucleus into account, during the emission process
  • E_1>E_2
  • E_1< E_2
  • E_1=E_2
  • Information insufficient
A 100 W point source emits monochromatic light of wavelength 6000\overset {o}{A}. Calculate the total number of photons emitted by the source per second.
  • 5\times 10^{20}
  • 8\times 10^{20}
  • 6\times 10^{20}
  • 3\times 10^{20}
An electron and a photon have same wavelength. If p is the momentum of electron and E is the energy of photon, the magnitude of p/E in S\space I unit is 
  • 3.0\times10^8
  • 3.33\times10^{-9}
  • 9.1\times10^{-31}
  • 6.64\times10^{-34}
An electron is in an excited state in a hydrogen like atom. It has a total energy of -3.4\space eV. The kinetic energy of electron is 'E\ ' and its de Broglie wavelength is '\lambda\ '
  • E = 6.8\space eV;\quad \lambda = 6.6\times10^{-10}\space m
  • E = 3.4\space eV;\quad \lambda = 6.6\times10^{-10}\space m
  • E = 3.4\space eV;\quad \lambda = 6.6\times10^{-11}\space m
  • E = 6.8\space eV;\quad \lambda = 6.6\times10^{-11}\space m
The energy of photon of green by Potential DIfference of 5000A^0. is
  • 3.459 \times 10^{-19} joule
  • 3.973 \times 10^{-19} joule
  • 4.132 \times 10^{-19} joule
  • 8453 \times 10^{-19} joule
An electron of mass 'm' and charge 'w' initially at rest gets accelerated by a constant electric field 'E'. The rate of change of de-Broglie wavelength of this electron at time 't' ignoring relativistic effects is
  • -\dfrac{h}{eEt^2}
  • -\dfrac{eht}{E}
  • -\dfrac{mh}{eEt^2}
  • \dfrac{h}{eE}
We wish to see inside an atom. Assume the atom to have a diameter of 100 pm. This means that one must be able to resolve a width of say 10 pm. If an electron microscope is used the energy required should be
  • 1.5 keV
  • 15 keV
  • 150 keV
  • 1.5 MeV
The energy of photon of wavelength \lambda is
  • c \lambda /h
  • h \lambda /c
  • hc/ \lambda
  • \lambda/ hc
The wavelength of a wave is \lambda = 6000 \overset{o}{A}, then wave number will be
  • 1.66 \times 10^{7} m^{-1}
  • 1.66 \times 10^{6} m^{-1}
  • 16.6 \times 10^{-1} m^{-1}
  • 166 \times 10^{3} m^{-1}
A proton and \alpha-particle are accelerated through the same potential difference. The ratio of their  de-Broglie wavelength will be
  • 1 : 1
  • 1 : 2
  • 2 :1
  • 2\sqrt 2 : 1
If the kinetic energy of a moving particle is E, then the de-Broglie wavelength is
  • \lambda =h \sqrt{2 m E}
  • \lambda =\sqrt{\dfrac{2 m E}{h}}
  • \lambda =\dfrac{h}{\sqrt{2 m E}}
  • \lambda =\dfrac{hE}{\sqrt{2 m E}}
If a photon and an electron have same de-broglie wavelength, then
  • Both have same kinetic energy
  • Proton has more K.E. than electron
  • Electron has more K.E. than proton
  • Both have same velocity
If the energy of a photon is 10 eV, then its momentum is :
  • 5.33 \times 10^{-23} kg \,m/s
  • 5.33 \times 10^{-25} kg \,m/s
  • 5.33 \times 10^{-29} kg \,m/s
  • 5.33 \times 10^{-27} kg \,m/s
It is essential to consider light as a stream of photons to explain
  • Diffraction of light
  • Refraction of light
  • Photoelectric effect
  • Reflection of light
A 200W sodium street lamp emits yellow light of wavelength 0.6\mu m. Assuming it to be 25% efficient converting electrical energy to light, the number of photons of yellow light it emits per second is :
  • 62\times 10^{20}
  • 3\times 10^{19}
  • 1.5\times 10^{20}
  • 6\times 10^{18}
Two hydrogen atoms are in excited state with electrons residing in \displaystyle n=2. First one is moving towards left and emits a photon of energy \displaystyle { E }_{ 1 } towards right. Second one is moving towards left with same speed and emits a photon of energy \displaystyle { E }_{ 2 } towards left. Taking recoil of nucleus into account during emission process, which of the following option is correct?
  • \displaystyle { E }_{ 1 }>{ E }_{ 2 }
  • \displaystyle { E }_{ 1 }<{ E }_{ 2 }
  • \displaystyle { E }_{ 1 }={ E }_{ 2 }
  • information insufficient
In photoelectric effect, ______ present in solar energy changes into electric energy.
  • Only radiant heat
  • Visible light
  • Both radiant heat and light
  • Neither radiant heat nor light
The condition for achieving laser action are
(i) the system must be in a state of population inversion
(ii) the excited state of the system should be in metastable state
(iii) the atom should be in lower energy state
(iv) no conditions required
  • (i) and (ii)
  • (ii) and (iii)
  • (iii) and (iv)
  • (i), (ii), (iii),(iv)
LASER action is found in _________ semiconductor.
  • direct bond gap
  • indirect bond gap
  • germanium
  • silicon
In LASER during the stimulated emission process the photon is __________.
  • lost
  • created
  • absorbed
  • scattered
If the energy of photons corresponding the wavelength of 6000\mathring { A } is 3.2\times {10}^{-19}J, the photon energy for a wavelength of 4000\mathring { A } will be
  • 1.11\times {10}^{-19}J
  • 2.22\times {10}^{-19}J
  • 4.44\times {10}^{-19}J
  • 4.80\times {10}^{-19}J
Consider two particles of different masses. In which of the following situations the heavier of the two particles will have smaller de-Broglie wavelength?
  • Both have a free fall through the same height
  • Both moves with the same kinetic energy
  • Both moves with the same linear momentum
  • Both move with the same speed
The momentum of a photon of energy 1MeV in kg-m/s, will be equal to :
  • 0.33\times {10}^{6}
  • 7\times {10}^{-24}
  • {10}^{-22}
  • 5\times {10}^{-22}
For the Bohr's first orbit of circumference 2\pi r, the de-Broglie wavelength of revolcing electron will be.
  • 2\pi r
  • \pi r
  • \displaystyle\frac{1}{2\pi r}
  • \displaystyle\frac{1}{4\pi r}
The energy of gamma \left( \gamma  \right) ray photon is { E }_{ \gamma  } and that of an X-ray photon is { E }_{ X }. If the visible light photon has an energy of { E }_{ v }, then we can say that:
  • { E }_{ X }>{ E }_{ \gamma }>{ E }_{ v }
  • { E }_{ \gamma }>{ E }_{ v }>{ E }_{ X }
  • { E }_{ \gamma }>{ E }_{ X }>{ E }_{ v }
  • { E }_{ X }>{ E }_{ v }>{ E }_{ \gamma }
The de-Broglie wavelength of an electron in the ground state of the hydrogen atom is :
  • \pi r^2
  • 2\pi r
  • \pi r
  • \sqrt{\pi r}
In photoelectric effect if the intensity of light is doubled, then maximum kinetic energy of photoelectrons will become.
  • Double
  • Half
  • Four times
  • No change
When the kinetic energy of an electron is increased the wavelength of the associated wave will :
  • Increase
  • Decrease
  • Wavelength does not upon kinetic energy
  • None of the above
The energy of an electron of mass m moving with velocity V and de-Broglie wavelength \lambda is __________. ('h' is Planck's constant)
  • \displaystyle\frac{h}{2m\lambda}
  • \displaystyle\frac{h^2}{2m\lambda^2}
  • \displaystyle\frac{h\lambda}{2m}
  • \displaystyle\frac{h}{m\lambda}
The de-Broglie wavelength of an electron moving with a velocity \dfrac{c}{2} (where c is velocity of light in vacuum) is equal to the wavelength of a photon. The ratio of the kinetic energies of electron and photon is:
  • 1 : 4
  • 1 : 2
  • 1 : 1
  • 2 : 1
1 mole of photon, each of frequency 2500{ s }^{ -1 }, would have approximately a total energy of :
  • 10 erg
  • 1 J
  • 1 eV
  • 1 MeV
Which of the following expression gives the de-Broglie relationship?
  • \displaystyle p=\frac { h }{ mv }
  • \displaystyle \lambda =\frac { h }{ mv }
  • \displaystyle \lambda =\frac { h }{ mp }
  • \displaystyle \lambda m=\frac { v }{ p }
Hard X-rays for the study of fractures in bones should have a minimum wavelength of \displaystyle { 10 }^{ -11 }m. The accelerating voltage for electrons in X-ray machine should be:
  • <124  \ kV
  • >124 \ kV
  • Between 60 \ kV and 70\  kV
  • =100\ kV
The energy of a photons is equal to the kinetic energy of a proton. If \lambda_1 is the de-Broglie wavelength of a proton, \lambda_2 the wavelength associated with the photon, and if the energy of the photon is E, then (\lambda_1/\lambda_2) is proportional to:
  • E^4
  • E^{1/2}
  • E^2
  • E
The energy that should be added to an electron to reduce its de-Broglie wavelength from 1nm to 0.5nm is.
  • Four times the initial energy
  • Equal to the initial energy
  • Twice the initial energy
  • Thrice the initial energy
Calculate the approximates energy of a photon given that wavelength of photon is 2 nm and Planck constant h is 6.6\times 10^{-34} Js.
  • 4\times 10^{-51}J
  • 1\times 10^{-34}J
  • 1\times 10^{-16}J
  • 1\times 10^{34}J
  • 2\times 10^{-50}J
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