CBSE Questions for Class 12 Medical Physics Dual Nature Of Radiation And Matter Quiz 11 - MCQExams.com

de-Broglie equation is 
  • $$n\lambda =2d\quad sin\theta $$
  • $$E=hv$$
  • $$E={ mc }^{ 2 }$$
  • $$\lambda =\dfrac { h }{ mv } $$
A proton has kinetic energy $$E=100keV$$ 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
  • $${E}^{2}$$
  • $${E}^{1/2}$$
  • $${E}^{-1}$$
  • $${E}^{-1/2}$$
The work function of metal is 1 eV. Light of wavelength 3000 A is incident on this metal surface. The velocity of emitted photo electrons will be
  • 10 m/s
  • 1 x $$10^3$$ m/s
  • 1 x $$10^4$$ m/s
  • 1 x $$10^6$$ m/s
In photoelectric effect, the momentum of incident photon of energy $$3 \times 10^{-19} J$$ is : 
  • $$9 \times 10^{11} kgms^{-1}$$
  • zero
  • $$10^{-27} kgms^{-1}$$
  • $$3 \times 10^{-11} kgms^{-1}$$
Among the following for which one mathemetical expression $$\lambda =\dfrac { h }{ p } $$ stands
  • De Broglie equation
  • Einstein
  • Uncertainty equation
  • Bohr equation
A photon of energy $$1.12 MeV$$ splits into electron - positron pair. The velocity of the electron is (in $$ms^{-1}$$)
  • $$3 \times 10^8$$
  • $$4.2 \times 10^8$$
  • $$1.32 \times 10^8$$
  • $$1.8 \times 10^8$$
Two particles of de-broglie wavelength $$\lambda_x$$ and $$\lambda_y$$ are moving in opposite directions. find dBroglie wavelength after perfectly inelastic collision:
  • $$\dfrac{\lambda_x \lambda_y}{\lambda_x - \lambda_y}$$
  • $$\dfrac{2\lambda_x \lambda_y}{\lambda_x - \lambda_y}$$
  • $$\dfrac{\lambda_x \lambda^2_y}{\lambda_x - \lambda_y}$$
  • $$\lambda_y - \lambda_x$$
Wavelength associated with an electron having kinetic energy $$ 3 \times 10^{-25} J$$ is $$x \times 10^{-7} \ m $$. What is the value of $$x$$?
  • 9
  • 4
  • 5
  • 6
Two particle of mass m and 2m moving in opposite direction collide head on. They have same de-Broglie wavelength before collision after the collision.
  • If e = 1, de-broglie wavelength of m is greater than that of 2 m
  • If e = 1, de-Broglie wavelength of 2 m is greater than that of m
  • The de-Broglie wavelength of m increases if e = 1
  • The de-Broglie wavelength of 2m remains same if e = 1
A photon possesses:
  • positive charge.
  • negative charge.
  • no charge
  • depends on the source of photon
A beam of light incident on a surface has photons each of energy $$1 mJ$$ and intensity $$25 \, w/cm^2$$. Find number of photons incident per second if surface area is $$25 \, cm^2$$.
  • $$6.25 \times 10^5 \, s^{-1}$$
  • $$8.25 \times 10^5 \, s^{-1}$$
  • $$6.25 \times 10^4 \, s^{-1}$$
  • $$5.25 \times 10^5 \, s^{-1}$$
The ratio of wavelengths of photons emitted when hydrogen atom de-excites from third excited state to second excited state an then de-excites form seconds excited state to first excited state is
  • $$\dfrac {7}{20}$$
  • $$\dfrac {20}{7}$$
  • $$5$$
  • $$20$$
If a proton and electron have same de Broglie wavelength, then
  • Kinetic energy of electron $$<$$ kinetic energy of proton
  • Kinetic energy of electron $$=$$ kinetic energy of proton
  • Momentum of electron $$=$$ momentum of proton
  • Momentum of electron $$<$$ momentum of proton
Mark the correct statement :
  • electrons are emitted from metal surface when light of sufficient wavelength falls on it.
  • the kinetic energy of photo electrons is more for light of longer wavelength in comparison to that due to shorter wavelength.
  • both of the above
  • none of the above
The function of photoclecrtic cell is
  • to convert electrical energy into light energy.
  • to convert light energy into electrical energy
  • to convert mechanical energy into electrical energy
  • to convert DC into AC.
The maximum velocity of the photoelectron emitted by the metal surface is $$v$$. Charge and mass of the photoelectron is denoted by $$e$$ and $$m$$ respectively. The stopping potential in volt is?
  • $$\dfrac{v^2}{2\left(\dfrac{m}{e}\right)}$$
  • $$\dfrac{v^2}{2\left(\dfrac{e}{m}\right)}$$
  • $$\dfrac{v^2}{\left(\dfrac{e}{m}\right)}$$
  • $$\dfrac{v^2}{\left(\dfrac{m}{e}\right)}$$
The de-Broglie wavelength of electron in $$3^{rd}$$ orbit of $$He^{+1}$$ ion is approximately.
  • $$2A^0$$
  • $$3A^0$$
  • $$4A^0$$
  • $$5A^0$$
A particle 'P' is formed due to a completely inelastic collision of particles 'x' and 'y' having de-Broglie wavelengths $$'\lambda_x'$$ and $$'\lambda_y'$$ respectively. If x and y were moving in opposite directions, then the de-Broglie wavelength of 'P' is?
  • $$\lambda_x+\lambda_y$$
  • $$\dfrac{\lambda_x\lambda_y}{\lambda_x+\lambda_y}$$
  • $$\dfrac{\lambda_x\lambda_y}{|\lambda_x-\lambda_y|}$$
  • $$\lambda_x-\lambda_y$$
When photons of energy $$h\nu$$ fall on metal plate of work function $$W_o$$, photoelectrons of maximum kinetic energy $$K$$ are ejected. If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be?
  • $$K+W_o$$
  • $$K+h\nu$$
  • $$K$$
  • $$2K$$
At one time the meter was defined as $$1650763.73$$ wavelength of the orange light emitted by a light source containing $$Kr^{86}$$ atoms. What is the corresponding photon energy of this radiation?
  • $$3.28\times 10^{-19}\ J/quanta$$
  • $$1.204\times 10^{-31}\ J/quanta$$
  • $$1.09\times 10^{-27}\ J/quanta$$
  • $$2.048\ J/quanta$$
Consider an electron in a hydrogen atom, revolving in its second excited state (having radius $$4.65 \mathring{A}$$). The de-Broglie wavelength of this electron is:
  • $$12.9 \mathring{A}$$
  • $$3.5 \mathring{A}$$
  • $$9.7 \mathring{A}$$
  • $$6.6 \mathring{A}$$
in a photoelectric effect experiment the threshold wavelength of the light is $$380nm$$. If the wavelength of incident light is $$260nm$$, the maximum kinetic energy electrons will be:
Given $$E(in \,eV)=\frac{1237}{\lambda(in\,nm)}$$
  • $$1.5eV$$
  • $$4.5eV$$
  • $$15.1eV$$
  • $$3.0eV$$
For the same speed, de Broglie wavelength.
  • Of electron is larger than proton
  • Of proton is larger than $$\alpha-particle$$
  • Of electron is larger than $$\alpha-particle$$
  • All of the above
Which of the following statements is false?
  • Material wave (de Broglie wave) can travel in vacuum
  • Electromagnetic wave can travel through vacuum
  • The velocity of photon is not the same whether light passes through any medium
  • Wavelength of de Broglie wave depends upon velocity
The energy of a photon of frequency $$f$$ is
  • $$hf$$
  • $$\dfrac {h}{f}$$
  • $$h^{2}f$$
  • $$h/f^{2}$$
The number of ejected photoelectrons increases with increase.
  • In frequency of light
  • In wavelength of light
  • In intensity of light
  • None of these
Two particles A and B of same mass have their total energies $$E_A$$ and $$E_B$$  in the ratio $$E_A:E_B=1:2$$. Their potential energies $$U_A$$ and $$U_B$$ are in the ratio $$U_A:U_B=1:2$$ . If $$\lambda_A$$ and $$\lambda_B$$ are their de-Broglie wavelengths, then $$\lambda_A:\lambda_B$$ is
  • $$1:2$$
  • $$2:1$$
  • $$1:\sqrt{2}$$
  • $$\sqrt{2}:1$$
  • $$1:1$$
What wavelength must electromagnetic radiation have if a photon in the beam has the same momentum as an electron moving with a speed $$1.1\times 10^5$$m/s(Planck's constant $$=6.6\times 10^{-34}$$J-s, rest mass of electron$$=9\times 10^{-31}$$kg?
  • $$\dfrac{2}{3}$$nm
  • $$\dfrac{20}{3}$$nm
  • $$\dfrac{4}{3}$$nm
  • $$\dfrac{40}{3}$$nm
  • $$\dfrac{3}{20}$$nm
It takes $$4.6eV$$ to remove one of the least tightly bound electrons from a metal surface. When monochromatic photons strike the metal surface, electrons having kinetic energy from zero to $$2.2eV$$ are ejected. What is the energy of the incident photons?
  • $$2.4eV$$
  • $$2.2eV$$
  • $$6.8eV$$
  • $$4.6eV$$
  • $$5.8eV$$
The speed of photon.
  • May be less than speed of light
  • May be greater than speed of light
  • Must be equal to speed of light
  • Must be less than speed of light
If the de Broglie wavelength of a proton is $$10^{-13} m$$, the electric potential through which it must have been accelerated is
  • $$4.07\times 10^{4}V$$
  • $$8.2\times 10^{4}V$$
  • $$8.2\times 10^{3}V$$
  • $$4.07\times 10^{5}V$$
What is the de-Broglie wavelength of the $$\alpha$$- particle accelerated through a potential difference $$V$$
  • $$\dfrac{0.287}{\sqrt V}\ A^o$$
  • $$\dfrac{12.27}{\sqrt V}\ A^o$$
  • $$\dfrac{0.101}{\sqrt V}\ A^o$$
  • $$\dfrac{0.202}{\sqrt V}\ A^o$$
An electron of mass $$m$$ and magnitude of charge $$|e|$$ 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:
  • $$\dfrac {-h}{|e| Et^2}$$
  • $$-\dfrac {h}{|e| Et}$$
  • $$-\dfrac {h}{|e| Et \sqrt t}$$
  • $$\dfrac {|e| Et}{h}$$
How many photons are emitted by a laser source of $$5\times 10^{-3} W$$ operating at $$632.2\ nm$$ in $$2$$ second? $$(h = 6.63\times 10^{-34} Js)$$.
  • $$3.2\times 10^{16}$$
  • $$1.6\times 10^{16}$$
  • $$4\times 10^{16}$$
  • None of these
Which one of the following is the correct graph between energy and wavelength for a given photon?
  • None of these
Photoelectic effect shows.
  • Wave-like behaviour of light
  • Particle-like behaviour of light
  • Both wave-like and particle-like behaviour of light
  • Neither wave-like nor particle-like behaviour of light
Two photons having
  • equal wavelengths have equal linear momenta
  • equal energies have equal linear momenta
  • equal frequencies have equal linear momenta
  • equal linear momenta have equal wavelengths
The equation E = pc is valid
  • for an electron as well as for a photon
  • for an electron but not for a photon
  • for a photon but not for an electron
  • neither for an electron nor for a photon
What is the energy of photon of wavelength $$24800\mathring{A}$$?
  • $$0.5\ eV$$
  • $$0.9\ eV$$
  • $$1.1\ eV$$
  • $$0.75\ eV$$
Two photons of same frequencies moving in same medium have
  • Same linear momenta and wavelengths
  • Same linear momenta and same speeds
  • Same energies and same linear momenta
  • None of the above
A radiation is incident on a metal surface of work function $$2.3\ eV$$. The wavelength of incident radiation is $$600\ nm$$. If the total energy of incident radiation is $$23\ J$$, then the number of photoelectrons is
  • Zero
  • $$> 10^{4}$$
  • $$= 10^{4}$$
  • None of these
A cylindrical rod of some laser material $$5\times 10^{-2}m$$ long and $$10^{-2}m$$ in diameter contains $$2\times 10^{25}$$ ion per $$m^3$$. If on excitation all the ions are in the upper energy level and de-excite simultaneously emitting photons in the same direction, calculate the maximum energy contained in a pulse of radiation of wavelength $$6.6\times 10^{-7}m$$. If the pulse lasts for $$10^{-7}$$s, calculate the average power of the laser during the pulse
  • $$33.55\ W$$
  • $$43.55\ W$$
  • $$23.55\ W$$
  • $$29.55\ W$$

Five volts of stopping potential is needed for the photoelectrons emitted out of a surface of work function $$2.2\,eV$$ by the radiation of wavelength
  • $$1719\,\overset{\circ}{A}$$
  • $$3444\,\overset{\circ}{A}$$
  • $$861\,\overset{\circ}{A}$$
  • $$3000\,\overset{\circ}{A}$$
The voltage applied to an X-ray tube is $$18 \ kV$$. The maximum mass of photon emitted by the X-ray tube will be
  • $$2 \times 10^{-13} \ kg$$
  • $$3.2 \times 10^{-36} \ kg$$
  • $$3.2 \times 10^{-32} \ kg$$
  • $$9.1 \times 10^{-31} \ kg$$

A particle of mass $$10^{-31},kg$$ is moving with a velocity equal to $$10^5 \,ms^{-I}$$ . The wavelength of the particle is equal to
  • $$0$$
  • $$6.6\times10^{-8}\,m$$
  • $$0.66\,m$$
  • $$1.5\times10^{-7}\,m$$

Monochromatic light incident on a metal surface emits electrons with kinetic energies
from zero to $$2.6\, eV$$. What is the least energy of the
incident photon if the tightly bound electron needs $$4.2 \,eV$$ to
remove?
  • $$1.6\,eV$$
  • From $$1.6\,eV\,to\,6.8\,eV$$
  • $$6.8\,eV$$
  • More than $$6.8\,eV$$
The de-Broglie wavelength associated with with the particle of mass $$m$$ moving with velocity $$v$$ is 
  • $$h/mv$$
  • $$mv/h$$
  • $$mh/v$$
  • $$m/vh$$
The de-Broglie wavelength associated with a hydrogen molecule moving with a thermal velocity of $$3\ km/s$$ will be 
  • $$1\ A^o$$
  • $$0.66\ A^o$$
  • $$6.6\ A^o$$
  • $$66\ A^o$$
If we express the energy of a photon in $$keV$$ and the wavelength in angstroms, then energy of a photon can be calculated from the relation
  • $$E=12.4\ hv$$
  • $$E=1.2\ h/ \lambda$$
  • $$E=12.4 / \lambda$$
  • $$E=hv$$
The de-Broglie wavelength of a neutron at $$27^oC$$ is $$\lambda$$. What will be its wavelength at $$927^oC$$
  • $$\lambda /2$$
  • $$\lambda /3$$
  • $$\lambda /4$$
  • $$\lambda /9$$
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