CBSE Questions for Class 12 Medical Physics Dual Nature Of Radiation And Matter Quiz 9 - MCQExams.com

Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?
The de Broglie wavelength $$\lambda $$ associated with a  proton increases by $$25\%$$. If its momentum is decreased by $$p_0$$. The initial  momentum was:
  • $$4 p_0$$
  • $$\dfrac{p_0}{4}$$
  • $$5p_0$$
  • $$\dfrac{p_0}{5}$$
A monochromatic beam of electromagnetic radiation has an intensity of $$1W/{m^2}$$ . Then the average number of photons per $${m^3}$$ for  a 10MeV $$\gamma $$ ray is ? 
  • 4166
  • 3000
  • 5000
  • 2083
When light of intensity $$1\ W/m^{2}$$ and wavelength $$5\times 10^{-7}m$$ is incident on a surface, it is completely absorbed by the surface. If $$100$$ photos emit one electron and area of the surface is $$1\ cm^{2}$$, then the photoelectric current will be
  • $$2\ mA$$
  • $$0.4\ \mu A$$
  • $$4.0\ mA$$
  • $$4\ \mu A$$
The De-Broglie wavelength associated with electrons revolving round the nucleus in a hydrogen atom in ground state, will be-
  • $$0.3\ A^{\circ}$$
  • $$3.3\ A^{\circ}$$
  • $$6.62\ A^{\circ}$$
  • $$10\ A^{\circ}$$
The de Broglie wavelength corresponding to the root-mean-square velocity of hydrogen molecules at temperature $$20^{o}\ C$$ is 
  • $$3.3A^{o}$$
  • $$1.04A^{o}$$
  • $$126A^{o}$$
  • $$34A^{o}$$
The ratio of $$d-$$Broglie wavelength of molecular of hydrogen and oxygen kept in two vessels separately at $$27^oC$$ and $$127^oC$$ respectively is:
  • $$\sqrt{\dfrac{4}{3}}$$
  • $$\sqrt{\dfrac{3}{32}}$$
  • $$\dfrac{8}{\sqrt{3}}$$
  • $$\dfrac{1}{8}$$
When a point source of light is at a distance of $$50cm$$ from a photoelectric cell, the cut -off voltage is found to be $$V_0$$.If the same source is placed at a distance of $$1m$$ from the cell,then the cut -off voltage will be:
  • $$V_0/4$$
  • $$V_0/2$$
  • $$V_0$$
  • $$2V_0$$
A proton is accelerated through $$225\, V$$. Its de Brogile wavelength is:
  • $$1.91\, pm$$
  • $$0.2\, pm$$
  • $$3\, pm$$
  • $$0.4 \,nm$$
 what is the angular momentum of an electron of de$$-$$broglie wavelength $$\lambda ?$$ given $$r$$ is the radius of orbit$$.$$
  • $$\dfrac{{rh}}{\lambda }$$
  • $$\dfrac{{2rh}}{\lambda }$$
  • $$\dfrac{{3rh}}{\lambda }$$
  • $$\dfrac{{4rh}}{\lambda }$$
According to de Broglie, wavelength of electron in second orbit is $$10^{-9}$$ meter. Then the circumference of orbit is :-
  • $$10^{-9}$$
  • $$2 \times 10^{-9}$$
  • $$3 \times 10^{-9}$$
  • $$4 \times 10^{-9}$$
Threshold wavelength of tungsten is 2300 angstrom. If ultraviolet light of wavelength 1800 angstrom is incident on it, then the maximum kinetic energy of photoelectrons would be ?
  • 1.5 eV
  • 2.5eV
  • 3.0 eV
  • 5.0eV
A particle is dropped from a height H. The de-Broglie wavelength of the particle as a function of height is proportional to
  • $$H$$
  • $$H\dfrac{1}{2}$$
  • $$H^o$$
  • $$H\dfrac{-1}{2}$$
A photon and an electron both have wavelength $$1A^{o}$$. The ratio of energy of photon to that of electron is
  • $$1$$
  • $$0.012$$
  • $$82.7$$
  • $$10^{-10}$$
The de-Broglie wavelength of an electron is the same as the wavelength of a photon. The K.E of photon is $$'x'$$ times the K.E of the electron,then $$'x'$$ is (m-mass electron ,h- planck's constant,c-velocity of light)
  • $$\dfrac{hc}{2\lambda m}$$
  • $$\dfrac{2m\lambda c}{h}$$
  • $$\dfrac{2\lambda c}{hm}$$
  • $$\dfrac{2\lambda m}{ch}$$
The radio of deBroglie wavelengths of a proton and an alpha particle of same energy is
  • $$1$$
  • $$2$$
  • $$4$$
  • $$0.25$$
A chlorine molecule with an initial velocity of $$600ms^{-1}$$ absorbs a photon of wavelength 350 nm and is then dissociated into two chlorine atoms. One of the atoms is detected moving perpendicular to the initial direction of the molecule and having a velocity of $$1600ms^{-1}$$. The binding energy of the molecule is (approx)? [Neglect the momentum of the absorbed photon. The relative atomic mass of chlorine is 35]
  • $$3.36\times 10^{-17}J$$
  • $$3.36\times 10^{-19}J$$
  • $$3.36\times 10^{-21}J$$
  • $$3.36\times 10^{-28}J$$
Electron has energy of 100 $${ e }{V }$$ what will be its wavelength
  • $$1.2{ \mathring { A } }$$
  • $$10 { \mathring { A } }$$
  • $$100 { \mathring { A } }$$
  • $$1 \mathring { A } $$
The de Broglie wavelength of an electron moving with a velocity $$1.5 \times{ 10 }^{ 8 }{ ms }^{ -1 }$$ is equal to that a photon. The ratio of the kinetic energy of the electron to the that of the photon is 
  • 2
  • 4
  • $$\dfrac { 1 }{ 2 }$$
  • $$\dfrac { 1 }{ 4 }$$
A photon and an electron both have wavelength $$1\mathring { A } $$. The ratio of energy of photon to that of electron is 
  • 1
  • 0.012
  • 82.7
  • $${ 10 }^{ -10 }$$
If the rest mass of an electron or positron is $$0.51\ MeV$$, then the kinetic energy of each particle, in the electron-positron pair produced by a $$\gamma-$$photon of $$2.42\ MeV$$, will be ?
  • $$0.3\ MeV$$
  • $$1.9\ MeV$$
  • $$0.7\ MeV$$
  • $$1.5\ MeV$$
An $$\alpha $$ particle is moving in a circular path of radius in the presence of magnetic field B. The de-Broglie wavelength associated with the particle will be $$(q\rightarrow charge\quad on\quad \alpha \quad particle)$$
  • $$\cfrac { hr }{ qB } $$
  • $$\cfrac { hB }{ qr } $$
  • $$\cfrac { h }{ qBr } $$
  • $$\cfrac { h{ r }^{ 2 } }{ qB } $$
A photon and an electron have equal energy $$E$$. $${\lambda _{photon}} \times {\lambda _{electron}}$$ is proportional to:
  • $$E^{\dfrac{-3}{2}} $$
  • $$\frac{1}{{\sqrt E }}$$
  • $$\frac{1}{E}$$
  • Does not depend upon E.
De-Broglie wavelength associated with thermal neutrons at room temperature of $$27^{0}$$C is :
  • $$1.452\times 10^{-10}$$m
  • $$2.57\times 10^{-10}$$
  • $$0.452\times 10^{-10}$$m
  • $$3.452\times 10^{-10}$$m
A particle of mass M at rest decays into particles of masses $$m_{1} \ and  \ m_{2}$$ having non -zero velocities. The ratio of the de broglie wavelengths of the particles $$\lambda _{1}/\lambda _{2}$$ is :
  • $$m _{1}/m _{2}$$
  • $$m _{2}/m _{1}$$
  • 1
  • m1.m2
The threshold frequency for a photosenstive metal is $$7 \times 10 ^ { 13 } \mathrm { Hz}$$. If light of frequency $$10 ^ {14 } \mathrm { Hz} $$ is incident on this metal, then maximum kinetic energy of emitted electron is?
  • $$4 \times 10 ^ { -20 } \mathrm {J}$$
  • $$8 \times 10 ^ { -20 } \mathrm {J}$$
  • $$2 \times 10 ^ { -20 } \mathrm {J}$$
  • $$10 ^ { -20 } \mathrm {J}$$
The ratio of wavelength of deutron and proton accelerated through the same potential difference will be-
  • $$\dfrac { 1 }{ \sqrt { 2 } }$$
  • $$\sqrt { \dfrac { 2 }{ 1 } }$$
  • $$\dfrac { 1 }{ 2 }$$
  • $$\dfrac { 2 }{ 1 }$$
A source S$$_{1}$$ is producing 10$$^{15}$$ photons per second of wavelength $$5000$$ $$A^o$$ . Another source S$$_{2}$$ is producing $$1.02 \times 10^{15}$$ photons per second of wavelength $$5100$$ $$A^o$$ .Then, $$\dfrac{(power \ of \ S_{2})}{(power \  of \ S_{1})}$$ is equal to
  • $$0.98$$
  • $$1.00$$
  • $$1.02$$
  • $$1.04$$
If Bohr radius is $$r_{0},$$ the corresponding de Broglie wavelength of the electron is 
  • $$\left ( \dfrac{2\pi }{r_{o}} \right )$$
  • $$\left ( \dfrac{r_{o} }{2\pi } \right )$$
  • $$\left ( \dfrac{1}{2\pi r_{o}} \right )$$
  • $${2\pi r_{o}} $$
Energy of a photon having wave number $$1.00 cm^{-1}$$ is 
  • $$6.62\times 10^{-34}$$ J
  • $$1.99\times 10^{-23}$$ J
  • $$6.62\times 10^{-32}$$ J
  • $$6.62\times 10^{-36}$$ J
Five elements $$A, B, C, D and E$$ have work functions $$1.2 eV, 2.4 eV, 3.6 eV , 4.8eV and 6.8 eV $$ respectively. If light of wavelength $$4000 A ^ { \circ }$$ is allowed to fall on these elements, then photoelectrons are emitted by
  • $$A, B and C$$
  • $$A, B, C, D and E$$
  • $$A and B$$
  • $$Only E$$
An electron beam has a kinetic energy equal to $$100\ eV$$. Find its wavelength associated with a beam, if mass of electron is $$9.1 \times 10 ^ { - 31 }\ kg$$ and  $$1 \text { eV } = 1.6 \times 10 ^ { - 19 } \mathrm { J }$$. (Planck's constant is $$6.6 \times 10 ^ { - 34 } \mathrm { J-s } )$$
  • $$24.6 \mathrm { A }^{o}$$
  • $$0.12 \mathrm { A }^{o}$$
  • $$1.2 A^{o}$$
  • $$6.3 \mathrm { A }^{o}$$
Photoeelectric work-function of a metal is $$ 1eV. $$ Light of wavelength $$ \lambda = 3000 \mathring { A } $$ falls on it. The photoelectrons come out with maximum velocity:
  • $$ 10 m/s $$
  • $$ 10^3 m/s $$
  • $$ 10^4 m/s $$
  • $$ 10^6 m/s $$
$$K_1$$ and $$K_2$$ are the maximum kinetic energies of the photo electrons emitted when light of wave lengths $$\lambda_1$$ and $$\lambda_2$$ respectively are incident on a metallic surface. If $$\lambda_1 = 3\lambda_2$$ then
  • $$K_1 > \dfrac{K_3}{3}$$
  • $$K_1 < \dfrac{K_2}{3}$$
  • $$K-1 > 3K_2$$
  • $$K_2 = 3K_1$$
When an electron de-excited back from $$(n+1)^th$$ state to $$n^th$$ state in a hydrogen like atoms, wavelength of radiation emitted is $$\lambda_{1}(n>>1)$$. In the same atom de-broglies wavelength associated with an electron in $$n^th$$ state is $$\lambda_{2}$$. Then $$\dfrac{\lambda_{1}}{\lambda_{2}}$$ is proportional to
  • $$\dfrac{1}{n}$$
  • $$n$$
  • $$n^{2}$$
  • $$n^{3}$$
When light is incident on surface, photo electrons are emitted. For photoelectrons:
  • The value of kinetic energy is same for all
  • Maximum kinetic energy do not depend on the
    wave length of incident light
  • The value of kinetic energy is equal to or less
    than a maximum kinetic energy
  • None of the above
The ratio of de-Broglie wavelengths of molecules of hydrogen and helium Which are at temperature $$27^oC$$ and $$127^oC$$ respectively is 
  • $$\dfrac { 1 }{ 2 } $$
  • $$\sqrt { \dfrac { 3 }{ 8 } } $$
  • $$\sqrt { \dfrac { 8 }{ 3 } } $$
  • $$1$$
The velocity of photons is proportional to (where $$v =$$ frequency) 
  • $$\dfrac { 1 } { \sqrt { v } }$$
  • $$v ^ { 2 }$$
  • $$\mathrm { v } ^ { 0 }$$
  • $$\sqrt { v }$$
If $$E_{1},E_{2},E_{3}$$ and $$E_{4}$$ the respectively kinetic energies of electron, decuteron proton and neutron having same de-Broglic wavelength, identity the correct in which those value would increase,
  • $$E_{2},E_{4},E_{3},E_{1}$$
  • $$E_{1},E_{3},E_{4},E_{2}$$
  • $$E_{2},E_{4},E_{1},E_{3}$$
  • $$E_{3},E_{1},E_{2},E_{4}$$
Find the maximum $$KE$$ of photo electrons liberated from the surface of lithium by electron magnetic radiation whose electric component varies with time as $$\varepsilon =a\left( 1+\cos { \omega t }  \right) \cos { { \omega  }_{ 0 } } t$$ where $$'a'$$ is a constant $$\left(\dfrac {\omega}{2\pi}\right) =6\times 10^{14}s^{-1}$$ and $$\left(\dfrac {\omega _{0}}{2\pi}\right) =0.66\times 10^{14}s^{-1}$$, work function of lithium $$=2.39\ eV$$  
  • $$0.72\ eV$$
  • $$0.36\ eV$$
  • $$0.603\ eV$$
  • $$0.99\ eV$$
A hydrogen atom emits a photon corresponding to an electron transition from n =5 to n=The recoil speed of hydrogen atom is almost  (mass of proton = $$1.6\times 10^{-27}\, kg$$)
  • $$10\ ms^{-1}$$
  • $$2\times10^{-2}\ ms^{-1}$$
  • $$4\ ms{-1}$$
  • $$8\times10^2\ ms^{-1}$$
If the debroglie wave-length of $$He$$ at $$927^{o}C$$ is $$\lambda$$ then de-brolie wave-length of $$CH_{4}(g)$$ at $$27^{o}C$$ will be
  • $$\lambda$$
  • $$\dfrac {\lambda}{2}$$
  • $$\dfrac {\lambda}{4}$$
  • $$2\lambda$$
The wavelength $$\lambda_{e}$$ of an electron and $$\lambda_{p}$$ of a photon of same energy $$E$$ are related by
  • $$\lambda_{p} \propto \lambda_{e}^{2}$$
  • $$\lambda_{p} \propto \lambda_{e}$$
  • $$\lambda_{p} \propto \sqrt {\lambda_{e}}$$
  • $$\lambda_{p} \propto \dfrac {1}{\sqrt {\lambda_{e}}}$$
An electron is moving in $${ 2 }^{ nd }$$ excited orbit of H-atom Radius of orbit in terms of de-Broglie wavelength $$\lambda $$ of electron can be given as
  • $$\cfrac { \lambda }{ \pi } $$
  • $$\cfrac { 2\lambda }{ \pi } $$
  • $$\cfrac { 3\lambda }{ 2\pi } $$
  • $$\cfrac { \lambda }{ 2\pi } $$
The work function of a metal is $$1.84\ eV$$. If the wavelength of incident photon is $$4000 \mathring{A}$$, Then the approximate maximum kinetic energy of emitted photoelectron will be 
  • $$1.25\ eV$$
  • $$3.1\ eV$$
  • $$0.58\ eV$$
  • $$1.8\ eV$$
The debroglie wavelength of photoelectrons is $$1\mathring {A}$$. Its accelerating potential is :
  • $$150\ V$$
  • $$15.3\ V$$
  • $$12.3\ V$$
  • $$13.6\ V$$
A parallel beam of uniform, monochromatic light of wavelength 2640 $$\overset { o }{ A } $$ has an intensity of 100 $$W/m^2$$. The number of photons in 1 $$mm^3$$ of this radiation are -
  • 266
  • 335
  • 442
  • 555
The momentum of a photon is $$2\times 10^{-16}$$ gm-cm/sec. Its energy is
  • $$0.61\times 10^{-26}$$ erg
  • $$2.0\times 10^{-26}$$ erg
  • $$6\times 10^{-6}$$ erg
  • $$6\times 10^{-8}$$ erg
The de Broglie wavelength of a gas molecule at a temperature T K is:
  • $$\cfrac{h}{\sqrt{3mKT}}$$
  • $$\cfrac{h}{3mKT}$$
  • $$\cfrac{h}{\sqrt{2mKT}}$$
  • $$\sqrt{2mKT}$$
A particle of mass m kg and charge q coulomb is accelerated from rest through V volt: then the de-Broglie wavelength $$\lambda$$ associated with it is given by 
  • $$\lambda = \frac{h}{\sqrt{mV}}$$
  • $$\lambda = \frac{h}{\sqrt{2mq}}$$
  • $$\lambda = \frac{h}{\sqrt{2mqV}}$$
  • $$\lambda = \frac{h}{\sqrt{2mV}}$$
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