CBSE Questions for Class 12 Medical Physics Dual Nature Of Radiation And Matter Quiz 4 - MCQExams.com

The de Broglie wavelength of an electron which falls through a p.d. of 10,000V is
  • 1.227 $$A^{0}$$
  • 12.27 $$A^{0}$$
  • 0.1227 $$A^{0}$$
  • 2.454 $$A^{0}$$

A proton has kinetic energy $$\mathrm{E}=100\mathrm{k}\mathrm{e}\mathrm{V}$$ which is equal to that of a photon. The wavelength of photon is $$\lambda_{2}$$ and that of proton is $$\lambda_{1}$$. The ratio of $$\lambda_{1}/\lambda_{2}$$ is proportional to
  • $$\mathrm{E}^{2}$$
  • $$\mathrm{E}^{1/2}$$
  • $$\mathrm{E}^{-1}$$
  • $$\mathrm{E}^{-1/2}$$
The wavelength $$\lambda_e$$ of an electron and $$\lambda_p$$ of a photon of same energy E are related by -
  • $$\lambda_p$$ $$\lambda_e^2$$
  • $$\lambda_p$$ $$\lambda_e$$
  • $$\lambda_p$$ $$\sqrt{\lambda_e}$$
  • $$\lambda_p$$ $$\frac{1}{\sqrt{\lambda_e}}$$
The hydrogen atom emits a photon of 656.3nm line. The momentum of the photon associated with it is
  • $$10^{-27}kgms^{-1}$$
  • $$10^{-23}kgms^{-1}$$
  • $$10^{-18}kgms^{-1}$$
  • $$10^{-15}kgms^{-1}$$
The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement ?


71421_0702913c909b4e15a9268e48e3d7c0ed.png
  • Curves (b) and (c) represent incident radiations same frequencies having same

    intensity.
  • Curves (a) and (b) represent incident radiations of different frequencies and

    different intensities
  • Curves (a) and (b) represent incident radiations of same frequencies but of

    different intensities
  • Curves (b) and (c) represent incident radiations of different frequencies and

    different intensities
Monochromatic light of frequency $$6.0\times 10^{14}$$ Hz is produced by a laser. The power emitted is $$2\times 10^{-3}$$W. The number of photons emitted, on the average, by the source per second is:
  • $$5\times 10^{14}$$
  • $$5\times 10^{15}$$
  • $$5\times 10^{16}$$
  • $$5\times 10^{17}$$
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 de Broglie wavelength associated with an electron of velocity 0.3c and rest mass $$9.1 \times 10^{-31}$$kg is
  • $$7.68\times 10^{-10}m$$
  • $$7.68\times 10^{-12}m$$
  • $$5.7\times 10^{-12}m$$
  • $$9.1\times 10^{-12}m$$
A source S$$_{1}$$ is producing 10$$^{15}$$ photons per second of wavelength 5000$$\dot{a}$$ . Another sorce S$$_{2}$$ is producing $$1.02 \times 10^{15}$$ photons per second of wavelength 5100$$\dot{A}$$ .Then, (power of S$$_{2}$$)/(power of S$$_{1}$$) is equal to
  • 1.00
  • 1.02
  • 1.04
  • 0.98
The photoelectric work function for a metal surface is 4.125 eV. The cut-off wavelength for this surface is:
  • $$4125 A^o$$
  • $$3000 A^o$$
  • $$6000 A^o$$
  • $$2062 A^o$$
A beam of light of wavelength $$\lambda$$ is incident on a mirror at an angle $$\theta$$. Find the change in momentum of the photon after reflection.
  • $$2 \dfrac{h}{\lambda}sin \theta$$
  • $$\dfrac{h}{\lambda} cos \theta$$
  • $$2 \dfrac{h}{\lambda}cos \theta$$
  • none of these
Mass of moving photon is
  • $$\frac {hv}{c^2}$$
  • $$\frac {hv}{c}$$
  • hv
  • Zero
The momentum of a photon having energy E is
  • $$\frac {E}{c}$$
  • $$\frac {E}{c^2}$$
  • $$\frac {E}{h}$$
  • Zero
A Photoelectric cell converts
  • Light energy into electrical eneregy
  • Light energy into sound energy
  • Electric energy into light energy
  • Light energy into heat energy
When light is incident on a surface, photoelectrons are emitted.
For those photoelectrons:
  • The value of kinetic energy is same
  • Kinetic energy does not depend on the wave length of incident light
  • The value of kinetic energy is equal to or less than a maximum energy
  • None of the above
In a photoelectric effect, the anode potential is plotted against the plate current
73339.jpg
  • A and B will have different intensities while B and C will have different frequencies
  • B and C will have different intensities while A and C will have different frequencies
  • A and B will have different intensities while A and C will have equal frequencies
  • A and B will have equal intensities while B and C will have different frequencies
Rest mass of a photon is
  • $$\frac {hv}{c^2}$$
  • $$\frac {hv}{c}$$
  • $$hv$$
  • zero
The photoelectric effect is described as the ejection of electrons from the surface of a metal when
  • It is heated to a high temperature
  • Light of suitable frequency falls on it
  • Electrons of suitable velocity impinge on it
  • It is placed in a strong magnetic field
Which of the following systems may be adequately described by classical physics?
  • Motion of a cricket ball
  • Motion of dust particle
  • A hydrogen atom
  • A neutron changing to a proton
A point of source of 6 watts emits monochromatic light of wavelength $$5000\dot A$$. The number of photons striking normally per second per unit area of the surface distant 5 m from the source will be
  • $$4.82$$
  • $$4.82 \space \times \space 10^{-4}$$
  • $$4.82 \space \times \space 10^{-6}$$
  • $$4.82 \space \times \space 10^{16}$$
A 40 watt bulb converts 6% of its power to red light (wavelength $$6500 \dot{A}$$). The number of red lights photons emitted by the bulb per second is
  • $$100$$
  • $$ 4 \times 10^{18}$$
  • $$ 8 \times 10^{18}$$
  • $$ 13 \times 10^{18}$$
A radio station emits $$10kW$$ power of $$90.8 MHz$$. Find the number of photons emitted per second
  • $$1.6 \times \displaystyle 10^{28}$$
  • $$\displaystyle 1.6\times 10^{29} $$
  • $$\displaystyle 1.6\times 10^{30} $$
  • $$\displaystyle 1.6\times 10^{32} $$
A laser used to weld detached retinas emits light with a wavelength of $$652  \displaystyle nm$$ in pulses that are of $$20  \displaystyle ms$$ duration. The average power during each pulse is $$0.6 \displaystyle W$$. Find the energy in each pulse in $$\displaystyle eV$$ and in a single photon.
  • $$\displaystyle 7.5\times 10^{15} eV, 1.9 eV$$
  • $$\displaystyle 7.5\times 10^{15} eV, 1.19 eV$$
  • $$\displaystyle 7.5\times 10^{16} eV, 0.19 eV$$
  • $$\displaystyle 7.5\times 10^{16} eV, 1.9 eV$$
A TV center transmits 10 kilowatt of power at 150 MHz. The energy of a photon of electromagnetic wave is
  • $$6\space \times 10^{-7} \space J$$
  • $$6\space \times 10^{-7} \space eV$$
  • $$6\space \times 10^{-17} \space J$$
  • $$6\space \times 10^{-17} \space eV$$
The energy of a photon of wavelength $$6000\dot A$$ in eV will be
  • 1.06 eV
  • 0.206 eV
  • 2.06 eV
  • 20 eV
A. The energy $$E$$ and momentum $$p$$ of a photon are related as $$p=\dfrac{E}{c}$$.

R. The photon behaves as a particle.
  • $$A $$ and $$R$$ are both correct and $$R$$ is correct explanation of $$A$$
  • $$A$$ and $$R$$ are correct but $$R$$ is not correct explanation of $$A$$
  • $$A$$ is correct but $$R$$ is false
  • Both $$A$$ and $$R$$ are false
If a proton and an electron have the same de Broglie wavelength, the ratio of the velocity of proton to the velocity of electron will be nearly
  • $$1$$
  • $$1840$$
  • $$\displaystyle\dfrac{1}{1840}$$
  • $$44$$
The hydrogen atom emits a photon of 656.3 nm line. Find the momentum of the photon associated with it.
  • $$ 10^{-27}$$ kg $$ms^{-1}$$
  • $$ 10^{-23}$$ kg $$ms^{-1}$$
  • $$ 10^{-25}$$ kg $$ms^{-1}$$
  • none of these
The energy that should be added to an electron to reduce its de broglie wavelength from 1 nm to 0.5 nm is 
  • Four times the initial energy.
  • Equal to initial energy.
  • Twice the initial energy.
  • Thrice the initial energy.
The wavelength associated with 1 $$MeV$$ proton is
  • 28.6 $$pm$$
  • 2.86 $$pm$$
  • 2.86 $$fm$$
  • 28.6 $$fm$$
The minimum energy required to dissociate $$Ag$$ $$Br$$ bond in 0.6 $$eV$$. A photographic flim is coated with a sliver bromide layer. Find the maximum wavelength whose signature can be recorded on the film
  • 207 $$nm$$
  • 702 $$nm$$
  • 207 $$A^{\circ}$$
  • 2070 $$nm$$
Find photon energy in $$eV$$
  • 1.04 $$eV$$
  • 1.14 $$eV$$
  • 1.72 $$eV$$
  • 1.28 $$eV$$
Find the wavelength of 100 $$eV$$ electron
  • $$1.227 \displaystyle A^{\circ}$$
  • $$1.72 \displaystyle A^{\circ}$$
  • $$1.24\displaystyle nm $$
  • $$12.4 \displaystyle nm $$
A surface has work function 3.3 $$eV$$ . Which of the following will cause emission?
  • 100 $$W$$ incandascent lamp
  • 40 $$W$$ flouroscent lamp
  • 20 $$W$$ sodium lamp
  • 20 $$W$$ Hg lamp
Find the wavelength of 10 $$MeV \ \alpha-$$particles
  • 3 $$A^{\circ}$$
  • 3 $$pm$$
  • 3 $$fm$$
  • 30 $$fm$$
In the following diagram if $$\displaystyle V_{2}>V_{1}$$then
153456.jpg
  • $$\displaystyle \lambda _{1}=\sqrt{\lambda _{2}}$$
  • $$\displaystyle \lambda _{1}<\lambda _{2}$$
  • $$\displaystyle \lambda _{1}=\lambda _{2}$$
  • $$\displaystyle \lambda _{1}>\lambda _{2}$$
The work function of a metal is 2.5 eV. When photon of some proper energy is made incident on it, then an electron of 1.5 eV is emitted. The energy of photon will be 
  • $$4 eV$$
  • $$1 eV$$
  • $$1.5 eV$$
  • $$2.5 eV$$
The number of photons of wavelength $$13.2$$ $$A^{0}$$ in $$6$$ $$J$$ of energy is:
($$h$$=$$6.6\times10^{-34}$$ $$Js$$)
  • $$2\times10^{12}$$
  • $$4\times10^{16}$$
  • $$6\times10^{20}$$
  • $$4\times10^{24}$$
The relation between energy E and momentum p of a photon is
  • $$E = pc$$
  • $$ E=\dfrac { p }{ c } $$
  • $$p = Ec$$
  • $$ E=\dfrac { { p }^{ 2 } }{ c } $$
The effective mass of photon of wavelength 40$$ \overset { \circ  }{ A } $$ will be:
  • $$ 55.2\times { 10 }^{ -35 }kg$$
  • $$ 55.2\times { 10 }^{ -33 }gm$$
  • $$ 55.2\times { 10 }^{ -17 }kg$$
  • $$ 55.2\times { 10 }^{ -38 }kg$$
Two electrons are moving with the same velocity, one electron enters a region of uniform electric field while the other enters a region of uniform magnetic field. Then, after sometime, if the de-Broglie wavelength of two are $$\lambda_{1}$$ and $$\lambda_{2}$$ respectively, then
  • $$\lambda_{1} = \lambda_{2}$$
  • $$\lambda_{1} > \lambda_{2}$$
  • $$\lambda_{1} < \lambda_{2}$$
  • $$\lambda_{1}>\lambda_{2}$$ or $$\lambda_{1}< \lambda_{2}$$

Find the minimum wavelength of X-ray produced if 10 kV potential difference is applied across the anode and cathode of the tube.
  • 12.4 A$$^{\circ}$$
  • 12.4 nm
  • 1.24 nm
  • 1.24 A$$^{\circ}$$
The correct curve between the energy of photon (E) and its wave length$$\ \lambda $$ is
A radio transmitter is working at frequency 880 kHz and power 10kW. The number of photons emitted per second will be 
  • $$\displaystyle 1327\times 10^{34}$$
  • $$\displaystyle 0.075\times 10^{-34}$$
  • $$\displaystyle 1.71\times 10^{31}$$
  • $$\displaystyle 13.27\times 10^{34}$$
The momentum of photon of frequency $$ { 10 }^{ 14 }Hz$$ will be
  • $$ 2.2\times { 10 }^{ -26 }Kg \ m/sec $$
  • $$ 2.21\times { 10 }^{ -28 }Kg \ m/sec $$
  • $$ { 10 }^{ -28 }Kg \ m/sec $$
  • $$ 0.21\times { 10 }^{ -2 }Kg \ m/sec $$
Protons are accelerated from rest by a potential difference 4 kV and strike a metal target. If a proton produces one photon on impact of minimum wavelength $$\lambda_1$$ and similarly an electron accelerated to 4 kV strikes the target and produces a minimum wavelength $$\lambda_2$$ then
  • $$\lambda_1 = \lambda_2$$
  • $$\lambda_1 > \lambda_2$$
  • $$\lambda_1 < \lambda_2$$
  • no such relation can be established
Neglecting variation of mass with energy the wavelength associated with an electron having a kinetic energy $$E$$ is proportional to 
  • $$E^{1/2}$$
  • $$E$$
  • $$E^{-1/2}$$
  • $$E^{-2}$$
When an electron moving at a high speed strikes a metal surface, which of the following are possible?
  • The entire energy of the electron may be converted into an X-ray photon
  • Any fraction of the energy of the electron may be converted into an X-ray photon.
  • The entire energy of the electron may get converted to heat.
  • The electron may undergo elastic collision with the metal surface.
An electron makes transition from $$n=4$$ to $$n=1$$ state in a hydrogen atom. The maximum possible number of photons emitted will be :
  • $$1$$
  • $$2$$
  • $$3$$
  • $$6$$
On increasing the applied potential difference in X-ray tube
  • The intensity of emitted radiation increases.
  • The minimum wavelength of emitted radiation increases.
  • The intensity of emitted radiation remains unchanged.
  • The minimum wavelength of emitted radiation decreases.
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