CBSE Questions for Class 12 Medical Physics Dual Nature Of Radiation And Matter Quiz 10 - MCQExams.com

The electron in the hydrogen atom jumps from the second orbit to the forth orbit after absorbing photon. In this process its:
  • energy doubles
  • angular momentum doubles
  • velocity doubles
  • linear momentum doubles
Photoelectrons are ejected from a metal when light of frequency v falls on it. Pick out the wrong statement from the following
  • No electrons are emitted if v less than W/h , where W is the work function of the metal
  • The ejected of the photoelectrons is instantaneous.
  • The maximum energy of the photoelectrons is hv.
  • The maximum energy of the photoelectrons is independent of the intensity of the light.
Which of the following statement is $$NOT$$ correct for the saturation current in a photoelectric cell ?
  • All the electrons emitted from the photosensitive plate reach collector.
  • The potential difference between the emitter and collector should be numerically equal to the stopping potential.
  • Collector is positive with respect to emitter.
  • It is the maximum current that can be set up in the photoelectric cell.
For wave connected with proton, de-broglie wavelength change by 0.25% if its momentum change by $$ P_0 $$ initial momentum=
  • $$ 100 P_0 $$
  • $$ \dfrac {P_0}{400} $$
  • $$ 401 P_0 $$
  • $$ \dfrac {P_0}{100} $$
Orbits of a particle moving in a circle are such that the perimeter of the orbit equals an integer number of de-Broglie wavelengths of the particle. For a charged particle moving in a plane perpendicular to a magnetic field, the radius of the nth orbital will therefore be proportional to  
  • $$n^2$$
  • n
  • $$n^{1/2}$$
  • $$n^{1/4}$$
The photoelectric effect can be understood on the basis of
  • The principle of superposition
  • The electromagnetic theory of light
  • The special theory of relativity
  • Line spectrum of the atom
Which of the  following is an to a possible de-Broglie's wavelength of a particle, which moves inside a cubical box of side length $$L$$, without losing any energy (elasticity colliding with walls of cube)?
1236273_808f39ff388444f0b8d82a7f1a5fb921.png
  • All of these
The circumstance of first of hydrogen atom is s.Then the Broglie wavelength of electron to that orbit is
  • $$\dfrac {S} {2}$$
  • $$2S$$
  • $$S$$
  • $$3S$$
A proton and an $$\alpha$$ particle are accelerated through the same potential difference V. The ratio of their de Broglie wavelengths is?
  • $$\sqrt{2}$$
  • $$2\sqrt{2}$$
  • $$\sqrt{3}$$
  • $$2\sqrt{3}$$
A particle $$A$$ of mass $$m$$ and initial velocity $$v$$ collides with a particle $$B$$ of mass $$\dfrac {m}{2}$$ which is at rest. The collision is held on, and elastic. The ratio of the de-Broglie wavelength $$\lambda_{A}$$ to $$\lambda_{B}$$ after the collision is
  • $$\dfrac {\lambda_{A}}{\lambda_{B}} = 2$$
  • $$\dfrac {\lambda_{A}}{\lambda_{B}} = \dfrac {2}{3}$$
  • $$\dfrac {\lambda_{A}}{\lambda_{B}} = \dfrac {1}{2}$$
  • $$\dfrac {\lambda_{A}}{\lambda_{B}} = \dfrac {1}{3}$$
Light of wavelength $$4000\overset { 0 }{ A } $$ is incident on a sodium surface for which the threshold wavelength of photoelectrons is $$5420\overset { 0 }{ A } $$. The work function of sodium is 
  • 0.57 eV
  • 1.14 eV
  • 2.29 eV
  • 4.58 eV
Figure represents the graph of photo-current $$I$$ versus applied voltage $$(V)$$. The maximum energy of the emitted photoelectron is-
1288990_abdce937a0fa4356a9fba20f7e2b458f.png
  • $$2eV$$
  • $$4eV$$
  • $$0eV$$
  • $$3eV$$
Two large parallel plates are connected with the terminal of $$100V$$ power supply. These plates have a fine hole at the centre. An electron having energy $$200eV$$  is so directed that it passes through the holes. When it comes out it's de-Broglie wavelength is
1305309_092204c2219145a184176a28be8240d8.png
  • $$1.22 A ^ { \circ }$$
  • $$1.75 A ^ { \circ }$$
  • $$2 A ^ { \circ }$$
  • none of these
The de-Broglie wavelength of a proton accelerated by $$400\ V$$ is
  • $$0.005\ \mathring {A}$$
  • $$1.0528\ \mathring {A}$$
  • $$0.0568\ \mathring {A}$$
  • $$0.0143\ \mathring {A}$$
Two particles A and B have de-Broglie's wavelengths $$30 \ \mathring A$$ and $$20 \ \mathring A$$, combined to form a particle C. Momentum is conserved in this process. The possible de-Broglie's wavelength of C is :
(the motion is one dimensional)
  • $$12 \ \mathring A$$
  • $$20 \ \mathring A$$
  • $$10 \ \mathring A$$
  • $$22 \ \mathring A$$
A proton and an electron are accelerated by same potential difference starting from rest have de- Brogile  wavelength $$\lambda _ { p }$$ and $$\lambda _ { e ^ { * } }$$ 
  • $$\lambda _ { e } = \lambda _ { p }$$
  • $$\lambda _ { 0 } < \lambda _ { p }$$
  • $$\lambda _ { e } > \lambda _ { p }$$
  • none of these
The number of photo electrons emitted for light of a frequency v (higher than the threshold frequency $$V_{0}$$)  is proportional to : - 
  • Frequency of light (v)
  • $$v - v_{o}$$
  • Threshold frequency $$(v_{o})$$
  • Intensity of light
Electron microscope is based on the principle
  • Photoelectric effect
  • wave nature of electron
  • Super conductivity
  • Laws of electro magneitc induction
The energies of three coservatives energy levels $${ l }_{ 3 }$$, $${ l }_{ 2 }$$ and $${ l }_{ 1}$$ of $${ E }_{ 0\quad  }\dfrac { { 4E }_{ 0 } }{ 9 } and\quad \dfrac { { E }_{ 0 } }{ 4 } $$ respectively. A photon of wavelength $$\lambda $$ $${ l }_{ 3 }\quad to\quad { l }_{}$$ What will be  the wavelength of emission for transition $${ l }_{ 3 }\quad to\quad { l }_{}$$ ?
  • $$\dfrac { 16\lambda }{ 31 } $$
  • $$\dfrac { 27\lambda }{ 7 } $$
  • $$\dfrac { 19\lambda }{ 20 } $$
  • $$\lambda $$
A heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio $$8:1$$. the ratio of de-broglie wavelengths of fragments are 
  • $$1:2$$
  • $$1:8$$
  • $$4:1$$
  • None of these
If a strong diffraction peak is observed when electron are incident at an angle. 'i' from the normal to the crystal planes with distance 'd' wavelength them (see figure) de Broglie wavelength $$ \lambda_{dB} $$ of electrons can be calculate by the relationship (n is an integer) 
  • $$ d sin = n \lambda_{dB} $$
  • $$2 d cos i= n \lambda_{dB} $$
  • $$ d sin = i \lambda_{dB} $$
  • $$ d cos = i \lambda_{dB} $$

The energy of a neutron in eV whose de-Broglie wavelength is $$1\mathop {\text{A}}\limits^{\text{0}} $$
  • $$1.67 \times {10^{ - 27}}eV$$
  • $$8.13 \times {10^{ - 2}}eV$$
  • $$6.62 \times {10^{ - 22}}eV$$
  • $$3.23 \times {10^{ - 2}}eV$$
The figure shows the path of white light's rays which leave in phase from two small source S$$_{1}$$ and S$$_{2}$$ and travel to a point X on a screen .The path difference  is S$$_{2}$$X -- S$$_{1}$$X = 10 $$\times 10^{-7}$$m.What wavelength of light give complete destructive interference at X?
  • 4.0$$\times 10^{-7}$$ m
  • 6.6$$\times 10^{-7}$$ m
  • 4.4$$\times 10^{-7}$$ m
  • 5.8$$\times 10^{-7}$$ m
If there is an increase in linear dimensions of the objects, the associated de-broglie wavelength.
  • Increases
  • Decreases
  • Remains unchanged
  • Depends on the density
If the deBroglie wavelenght of an electron is equal to $$10^{3}$$ times the wavelength of a photon of frequency $$6 \times 10^{14} Hz$$, then the speed of electron is equal to : (Speed of light = $$3 \times 10^8 m/s$$ Planck's constant = $$6.63 \times 10^{34} J$$ . Mass of  electron = $$9.1 10^{31} kg$$)
  • $$1.45\times 10^6m/s$$
  • $$1.75\times 10^6m/s$$
  • $$1.8\times 10^6m/s$$
  • $$1.1\times 10^6 m/s$$
If the particles listed below all have the same kinetic energy, which one would posses the shortest de-Broglie wavelength.
  • Electron
  • $$\alpha -$$particle
  • Proton
  • All of the above
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:
  • $$4:1$$
  • $$2:1$$
  • $$1:2$$
  • $$1:4$$
What is difference between laser and normal light?
  • Both light are polarized
  • Normal light is polarized but laser light is not
  • Both light are not polarized
  • Normal light is  not polarized but laser is polarized
A photon of energy $$8eV$$ is incident on metal surface of threshold frequency $$1.6\times 10^{15}Hz$$. The maximum kinetic energy of the photoelectrons emitted (in eV) (Take $$h = 6\times 10^{-34} Js)$$.
  • $$1.4\ eV$$
  • $$2.4\ eV$$
  • $$4.8\ eV$$
  • $$0.8\ eV$$
  • $$7\ eV$$
The de-Broglie wavelength $$(\lambda _B)$$ associated with the electron orbiting in the second excited state of hydrogen atom is relared to that in the ground state $$(\lambda _G)$$ by:
  • $$(\lambda _B=3 {\lambda _G})$$
  • $$(\lambda _B=2 {\lambda _G})$$
  • $$(\lambda _B=3 {\lambda _{G/3}})$$
  • $$(\lambda _B=3 {\lambda _{G/2}})$$

A non-monochromatic light is used in an experiment on the photoelectric effect. The stopping potential is related to the:
  • Mean wavelength
  • Longest wavelength
  • Shortest wavelength
  • None of the above
The graph between $$\dfrac { 1 } { \lambda }$$ and stopping potential $$\mathrm { V } _ { 0 }$$ of two metals having work functions $$\phi _ { 1 }$$ and $$\phi _ { 2 }$$ in an experiment of photoelectric effect is obtained as shown in the figure. Find out :
1377862_c17f17f3015844018e01a888f9463be7.png
  • Threshold wavelength of both metals
  • $$\phi _ { 1 } : \phi _ { 2 }$$
  • Which metal can emit photoelectrons with visible light?
  • $$\phi_{2 } : \phi_{2}$$
A bulb of 40 W is producing a light of wavelength 620 nm with 80% of efficiency, then the number of photons emitted by the bulb in 20 seconds are 
$$\left( 1{ eV }=1.6\times { 10 }^{ -19 }J,hc=12400eV \right) $$
  • $$2\times { 10 }^{ 18 }$$
  • $${ 10 }^{ 18 }$$
  • $${ 10 }^{ 21 }$$
  • $$2{ \times 10 }^{ 21 }$$
A photon and an eletron both have wavelength 1A . The ratio of energy of photon to that of eletron is
  • 1
  • 0.012
  • 82.35
  • $$10^{-10}$$
A photon falls through a height of $$1 km$$ through the earth's gravitational field. To calculate the change in its frequency, take its mass to be $$hv/C^2$$. The fractional change in frequency $$v$$ is close to :
  • $$10^{-20}$$
  • $$10^{17}$$
  • $$10^{-13}$$
  • $$10^{10}$$
If velocity of a particle is 3 times of that of electron and ratio of de brogile wavelength  of particle to that of electron is $$1.814\times { 10 }^{ -4 }.$$ The particle will be:-
  • Neutron
  • Deutron
  • Alpha
  • Tritium
The energy of photon of visible light with maximum wavelength in $$eV$$ is:
  • $$1$$
  • $$1.6$$
  • $$3.2$$
  • $$7$$
A particle moves in a closed orbit around the origin, due to a force which is directed towards the origin. The de Broglie wavelength of the particle varies cyclically between two values $${ \lambda  }_{ 1 }$$ and $${ \lambda  }_{ 2 }$$ with $${ \lambda  }_{ 1 }>{ \lambda  }_{ 2 }.$$ Which of the following statement is true?
  • The particle could be moving in an circular orbit with origin as centre
  • The particle could be moving in an parabolic orbit with origin as its focus
  • When the de Broglie wave length is $${ \lambda }_{ 1 },$$ the particle is nearer the origin than when its value is $${ \lambda }_{ 2 }$$.
  • When the de Broglie wavelength is $${ \lambda }_{ 2 },$$ the particle is nearer the origin than when its value is $${ \lambda }_{ 1 }$$.
The de Broglie wavelength of an electron moving with a velocity $$2.25 \times 10^8$$ $$ms^{-1}$$ is equal to that of a photon. The ratio of the kinetic energy of the electron to that of the energy of photon is :
  • $$\dfrac{3}{8}$$
  • $$4$$
  • $$\dfrac{1}{2}$$
  • $$2-\sqrt 3$$
During an experiment an $$\alpha $$-particle and a proton are accelerated by same positive difference , their de broglie wavelength ratio will (Take mass of proton= mass of neutron).
  • $$1:2$$
  • $$1:4$$
  • $$1:2\sqrt { 2 } $$
  • $$1:\sqrt { 2 } $$
You are given an electron with a deBroglie wavelength of $$\lambda =76.3$$ nm. What is the Kelvin temperature of this electron ? 
  • 1.50
  • 2.00
  • 2.50
  • 3.00
During an experiment an $$\alpha $$- particle and a proton are having a difference , their de Broglie wavelenght ratio will be

  • $$1:2$$
  • $$1:4$$
  • $$1:2\sqrt { 2 } $$
  • none of these
A photon collides with a stationary hydrogen atom is ground state inelastically. Energy the colliding photon is $$10.2 eV$$. After atime interval of the order of micro second another photon collides with same hydrogen atom inelatically with an energy of $$15 eV$$. What will be observed by the detector?
  • $$2$$ photons of energy $$10.2 eV$$
  • $$2$$ Photons of energy $$1.4 eV$$
  • One photon of energy $$10.2 eV$$ and an electron of energy $$1.4 eV$$
  • One photon of energy $$10.2 eV$$ and another photon of energy $$1.4 eV$$
If the de-Broglie wavelengths associated with a proton and $$  \alpha  $$ -particle are equal, then the ratio of velocities of the proton and the a-particle will be:
  • $$4:1$$
  • $$2:1$$
  • $$1:2$$
  • $$1:4$$
An electron with an initial kinetic energy of $$100\ eV$$ is accelerated through a potential difference of $$50\ V$$. Now the de-Broglie wavelength of electron becomes
  • $$1\ \overset{o}{A}$$
  • $$\sqrt{1.5}\ \overset{o}{A}$$
  • $$\sqrt 3\ \overset{o}{A}$$
  • $$12.27\  \overset{o}{A}$$
The smallest quantum of energy is:-
  • All
  • Electron
  • Proton
  • Photon
The ratio of de-Broglie wavelengths of molecules of hydrogen and helium which are at temperature $$27^oC$$ and $$127^oC$$ respectively is
  • $$\dfrac{1}{2}$$
  • $$2$$
  • $$\sqrt{\dfrac{8}{3}}$$
  • $$1$$
If h is the planck's constant, the momentum of a photon of wavelength 0.01 A is :
  • $$h \times 10^{-2}$$
  • h
  • $$h \times 10^2$$
  • $$h \times 10^{12}$$
If a photon having wavelength $$6.2 { nm }$$ was allowed to strike a metal plate having work function $$50 { eV }$$, then calculate wavelength associated with emitted electron.
  • $$1 \times 10 ^ { - 10 } \mathrm { m }$$
  • $$2\times 10 ^ { - 10 } \mathrm { m }$$
  • $$3 \times 10 ^ { - 18 } \mathrm { m }$$
  • $$4 \times 10 ^ { - 14 } \mathrm { m }$$
A photon of wavelength $$\lambda$$ is incident on a free electron at rest and scattered in backward direction with a wavelength $$2\lambda$$. The ratio of kinetic energy and movement of the electron will be (Assume Newtonian mechanics applies)
  • $$C 3$$
  • $$C 6$$
  • $$C 9$$
  • $$C {12}$$
0:0:1


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