Processing math: 7%

CBSE Questions for Class 12 Medical Physics Dual Nature Of Radiation And Matter Quiz 7 - MCQExams.com

The minimum intensity of light to be detected by human eye is 1010W/m2. The number of photons of wavelength 5.6×107m entering the eye, with pupil area 106m2, per second for vision will be nearly
  • 100
  • 200
  • 300
  • 400
If alpha particle, proton and electron move with the same momentum, then their respective de-Broglie wavelengths λα,λp,λe are related as
  • λα=λp=λe
  • λα<λp<λe
  • λα>λp>λe
  • λp>λe>λα
  • λp<λe<λα
De-Broglie wavelength of a body of mass 1kg moving with velocity of 2000m/s is?
  • 3.32×1027oA
  • 1.5×107oA
  • 0.55×1022oA
  • None of these
In a photoemissive cell with exciting wave length λ, the fastest electron has a speed v. If the exciting wavelength is change to 3λ/4, then the speed of the fastest emitted electron will be
  • v(34)12
  • v(43)12
  • Less than v(43)12
  • Greater than v(43)12
The de-Broglie wavelength of a neutron at { 27 }^{ o }C is \lambda . What will be its wavelength at { 927 }^{ o }C?
  • \lambda /2
  • \lambda /3
  • \lambda /4
  • \lambda /9
Threshold wavelength of a metal is 4000\overset{o}{A}. If light of wavelength 3000\overset{o}{A} irradiates the surface, the maximum kinetic energy of photoelectron is?
  • 1.7eV
  • 1.6eV
  • 1.5eV
  • 1.0eV
The de-Broglie wavelength of an electron and the wavelength of a photon are the same. The ratio between the energy of that photon and the momentum of that electron is (c =velocity of light, h= Planck's constant)
  • h
  • c
  • \dfrac {1}{c}
  • None of these
The speed of an electron having a wavelength of { 10 }^{ -10 }m is
  • 4.24\times { 10 }^{ 6 }m/s\quad
  • 5.25\times { 10 }^{ 6 }m/s
  • 6.26\times { 10 }^{ 6 }m/s\quad
  • 7.25\times { 10 }^{ 6 }m/s\quad
If alpha particle and deutron move with velocity v and 2v respectively, the ratio of their de-Broglie wavelength will be _____
  • 2 : 1
  • 1 : \sqrt {2}
  • 1 : 1
  • \sqrt {2} : 1

The energies of the incident photons are 3,4,5\,eV. The work functions of the metals are 0.5,1.5,2.5\,eV. The maximum K.E.s of the photoelectrons are in the ratio:

  • 3:4:5
  • 1:3:5
  • 1:1:1
  • 5:3:1
If the kinetic energy of free electron is made double; the new de-Broglie wavelength will be __________ times that of initial wavelength.
  • \dfrac { 1 }{ \sqrt { 2 } }
  • \sqrt { 2 }
  • 2
  • \dfrac { 1 }{ 2 }
Light of wavelength \lambda falls on a metal having work function \cfrac { hc }{ { \lambda  }_{ 0 } } . Photoelectric effect will take place only if
  • \lambda \ge { \lambda }_{ 0 }
  • \lambda \ge 2{ \lambda }_{ 0 }
  • \lambda \le { \lambda }_{ 0 }
  • \lambda =4{ \lambda }_{ 0 }
A body of mass 100 g moves at the speed of 36 { km }/{ h }. The de-Broglie wavelength related to it is of the order _________ m.
\left( h=6.626\times { 10 }^{ -34 }Js \right)
  • { 10 }^{ -24 }
  • { 10 }^{ -14 }
  • { 10 }^{ -34 }
  • { 10 }^{ -44 }
If the linear momentum of a particle is 2.2 \times 10^4\, kg\, ms^{-1}, then what will be its de-Broglie wavelength ? (Take hr. 6.6 \times 10^{-34}\, Js
  • 3 \times 10^{-29}\, m
  • 3 \times 10^{-29}\, nm
  • 6 \times 10^{-29}\, m
  • 6 \times 10^{-29}\, nm
The wavelength \lambda of a photon and the de-Broglie wavelength of an electron have the same value. Find the ratio of energy of photon of the kinetic energy of electron in terms of mass m, speed of light c and planck constant.
  • \displaystyle\frac{\lambda mc}{h}
  • \displaystyle\frac{hmc}{\lambda}
  • \displaystyle\frac{2hmc}{\lambda}
  • \displaystyle\frac{2\lambda mc}{h}
What is the photon flux and photon density at 2 m from the lamp?
  • 5.9\times 10^{14} photons cm^{-2}, 2\times 10^4 photons cm^{-2}
  • 2\times 10^4 photons cm^{-2}, 5.9\times 10^{14} photons cm^{-2}
  • 5.9\times 10^{10} photons cm^{-2}, 2\times 10^3 photons cm^{-2}
  • 2\times 10^3 photons cm^{-2}, 5.9\times 10^{10} photons cm^{-2}
An electron in an electron microscope with initial velocity v_0i enters a region of a stray transverse electric field E_0j. The time taken for the change in its de Broglie wavelength from the initial value of \lambda to \dfrac{\lambda}{3} is proportional to.
  • E_0
  • \displaystyle\frac{1}{E_0}
  • \displaystyle\frac{1}{\sqrt{E_0}}
  • \displaystyle\sqrt{E_0}
The approximate number of photons in a femtosecond (10^{-15}s) pulse of 600 nanometers wavelenghth light from a 10-kilowatt peak-power dye laser is
  • 10^3
  • 10^7
  • 10^{11}
  • 10^{15}
  • 10^{18}
An electron and a photon have same wavelength of 10^{-9}m. If E is the energy of the photon and p is the momentum of the electron, the magnitude of E/p in SI units is?
  • 1.00\times 10^{-9}
  • 1.50\times 10^8
  • 3.00\times 10^8
  • 1.20\times 10^7
The energy of a K-electron in tungsten is -20keV and of an L-electrons is -2keV. The wavelength of X-rays emitted when there is electron jump from L to K shell:
  • 0.3443\mathring { A }
  • 0.6887\mathring { A }
  • 1.3982\mathring { A }
  • 2.78\mathring { A }
The formula of kinetic mass of photon is? Where h is Planck's constant, v is frequency of the photon and c is its speed.
  • \displaystyle\frac{hv}{c}
  • \displaystyle\frac{hv}{c^2}
  • \displaystyle\frac{hc}{v}
  • \displaystyle\frac{c^2}{hv}
A particle is projected horizontally with a velocity 10\ m/s. What will be the ratio of de-Broglie wavelengths of the particle, when the velocity vector makes an angle 30^{\circ} and 60^{\circ} with the horizontal?
  • \sqrt {3} : 1
  • 1 : \sqrt {3}
  • 2 : \sqrt {3}
  • \sqrt {3} : 2
de-Broglie wavelength of atom at TK absolute temperature will be
  • \cfrac { h }{ mKT }
  • \cfrac { h }{ \sqrt { 3mKT } }
  • \cfrac { \sqrt { 2mKT } }{ h }
  • \sqrt { 2mKT }
The momentum associated with photon is given by __________.
  • h \upsilon
  • \displaystyle \frac{h \upsilon}{c}
  • h E
  • h \lambda
An electron of mass m with an initial velocity \overrightarrow{V}=V_0\hat{i}(V_0 > 0) enters an electric field \overrightarrow{E}=-E_0\hat{i}(E_0=constant > 0) at t=0. If \lambda_0 is its de-Broglie wavelength initially, then its de-Broglie wavelength at time t is?
  • \lambda_0\left(\displaystyle 1+\frac{eE_0}{mV_0}t\right)
  • \lambda_0 t
  • \displaystyle\frac{\lambda_0}{\left(\displaystyle 1+\frac{eE_0}{mV_0}t\right)}
  • \lambda_0
A charged particle is accelerated from rest through a certain potential difference. The de Broglie wavelength is { \lambda  }_{ 1 } when it is accelerated through {V}_{1} and is { \lambda  }_{ 2 } when accelerated through {V}_{2}. The ratio { \lambda  }_{ 1 }/{ \lambda  }_{ 2 } is
  • { V }_{ 1 }^{ 3/2 }:{ V }_{ 2 }^{ 3/2 }
  • { V }_{ 2 }^{ 1/2 }:{ V }_{ 1 }^{ 1/2 }
  • { V }_{ 1 }^{ \cfrac { 1 }{ 2 } }:{ V }_{ 2 }^{ \cfrac { 1 }{ 2 } }
  • { V }_{ 1 }^{ 2 }:{ V }_{ 2 }
An electron of mass m and a photon have same energy E.Find out the ratio of de-Brogile wavelength associated with them is (c- velocity of light)
  • c { \left[ 2mE \right] }^{ \dfrac { 1 }{ 2 } }
  • \dfrac { 1 }{ c } { \left[ \dfrac { 2m }{ E } \right] }^{ \dfrac { 1 }{ 2 } }
  • \dfrac { 1 }{ c } { \left[ \dfrac { E }{ 2m } \right] }^{ \dfrac { 1 }{ 2 } }
  • { \left[ \dfrac { E }{ 2m } \right] }^{ \dfrac { 1 }{ 2 } }
A material particle with a rest mass m_0 is moving with a velocity of light c. Then determine the wavelength of the de Broglie wave associated with it is.
  • \displaystyle(h/m_0c)
  • zero
  • \displaystyle\infty
  • \displaystyle(m_0c/h)
The frequencies of X-rays, \gamma rays and Ultra violet rays are respectively incident on a metal, having work function is 0.5eV. The ratio of maximum speed of emtted electrons is
  • p< q, q> r
  • p> q, q >r
  • p< q, q< r
  • p> q, q< r
About 5% of the power of a 100W light bulb is converted to visible radiation.What is the average intensity of visible radiation at distance of 10 m.
  • 0.4 W / m^2
  • 0.04 W / m^2
  • 0.004 W / m^2
  • 0.0004 W / m^2
Choose the correct answer from the alternatives given.
The photon energy in units of eV for electromagnetic waves of wavelength 2\ cm is then
  • 2.5 \, \times \, 10^{-19}
  • 5.2 \, \times \, 10^{16}
  • 3.2 \, \times \, 10^{-16}
  • 6.2 \, \times \, 10^{-5}
A 100 W sodium lamp radiates energy uniformly in all directions. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is incident on it. The  wavelength of the sodium light is 589 nm. The number of photons delivered per second to the sphere is
  • 3 \, \times \, 10^{15}
  • 3 \, \times \, 10^{10}
  • 3 \, \times \, 10^{20}
  • 3 \, \times \, 10^{19}
A blue lamp mainly emits light of wavelength 4500 \mathring{A}. The lamp is rated at 150 W and 8% of the energy is emitted as visible light. The number of photons emitted by the lamp per second is:
  • 3 \, \times \, 10^{19}
  • 3 \, \times \, 10^{24}
  • 3 \, \times \, 10^{20}
  • 3 \, \times \, 10^{18}
Which of the following functions is performed by a photo-electric cell?
  • It converts electrical energy into light
  • It converts light energy into electrical energy
  • It conserves sound energy
  • It converts electrical energy into sound
If h is Plancks constant, the momentum of a photon of wavelength 0.01 A^o is
  • 10^{-2}h
  • h
  • 10^2
  • 10^{12}h
A laser beam is for locating distant objects because
  • it is monochromatic
  • it is constant
  • it is not observed
  • it has small angular spread
The maximum value of photoelectric current is called:
  • base current
  • Saturation current
  • collector current
  • emitter current
The energy flux of sunlight reaching the surface of the earth is 1.388 \, \times \, 10^3 Wm^{-2}. The photons in the sunlight have an average wavelength of 550 nm. How many photons per square metre are incident on the earth per second?
  • 4 \, \times \, 10^{21}
  • 4 \, \times \, 10^{34}
  • 4 \, \times \, 10^{31}
  • 4 \, \times \, 10^{28}
The wavelength of light in the visible region is about 390 nm for violet colour and about 760 nm for red colour. The energy of photon in eV at violet end is
  • 2.32
  • 3.19
  • 1.42
  • 4.13
The linear momentum of a 3 MeV photon is:
  • 0.01 eV \, sm^{-1}
  • 0.02 eV \, sm^{-1}
  • 0.03 eV \, sm^{-1}
  • 0.04 eV \, sm^{-1}
A proton, a neutron, an electron and an \alpha-particle have same energy. Then their de Broglie wavelengths compare as :
  • \lambda_p\, = \,\lambda_n\, > \,\lambda_e \,> \,\lambda_\alpha
  • \lambda_\alpha\, < \,\lambda_p\, = \,\lambda_n \,< \,\lambda_e
  • \lambda_e\, < \,\lambda_p\, = \,\lambda_n \,> \,\lambda_\alpha
  • \lambda_e\, = \,\lambda_p\, = \,\lambda_n \, = \,\lambda_\alpha
When the velocity of an electron increases, its de Broglie wavelength:
  • increases
  • decreases
  • remains same
  • may increase or decrease
The de Broglie wavelength of an electron in a metal at 27^{\circ}C is (Given \, m_e \, = \, 9.1 \, \times \, 10^{-31} \, kg,\,  k_B \, = \, 1.38 \, \times \, 10^{-23} \, J \, K^{-1}) 
  • 6.2 \, \times \, 10^{-9} \, m
  • 6.2 \, \times \, 10^{-10} \, m
  • 6.2 \, \times \, 10^{-8} \, m
  • 6.2 \, \times \, 10^{-7} \, m
A monochromatic light of frequency 3 \, \times \, 10^{14} \, Hz is produced by a LASER, emits the power of 3 \, \times \, 10^{-3}\, W. Find how many numbers of photons are emitted per second.
  • 1.5 \, \times \, 10^{16}
  • 2.5 \, \times \, 10^{16}
  • 4.5 \, \times \, 10^{16}
  • 8.5 \, \times \, 10^{16}
A particle of mass 4m at rest decays into two particles of masses m and 3m having non-zero velocities. The ratio of the de Broglie wavelengths of the particles 1 and 2 is:
  • \dfrac{1}{2}
  • \dfrac{1}{4}
  • 2
  • 1
There are two sources of light, each emitting with a power of 100 W. One emits X-rays of wavelength 1 nm and the other visible light of 500 nm. The ratio of number of photons of X-rays to the photons of visible light of the given wavelength is:
  • 1:500
  • 1:400
  • 1:300
  • 1:200
Relativistic corrections become necessary when the expression for the kinetic energy \dfrac{1}{2} mv^2, becomes comparable with mc^2, where m is the mass of the particle. At what de Broglie waxelength will relativistic corrections become important for an electron?
  • \lambda \, = \, l \, nm
  • \lambda \, = \, l0 \, nm
  • \lambda \, = \, l0^{-1} \, nm
  • \lambda \, = \, l0^{-4} \, nm
Consider the four gases hydrogen, oxygen, nitrogen and helium at the same temperature. Arrange them in the increasing order of the de Broglie wavelengths of their molecules.
  • Hydrogen, helium, nitrogen, oxygen
  • Oxygen, nitrogen, hydrogen, helium
  • Oxygen, nitrogen, helium, hydrogen
  • Nitrogen, oxygen, helium, hydrogen
Two particles A_1 and A_2 of masses m_1, \, m_2 \, (m_1 \, > \, m_2) have the same de Broglie wavelength. Then
  • their momenta are the same.
  • their energies are the same.
  • momentum of A_1 is less than momentum of A_2
  • energy of A_1 is more than the energy of A_2
A particle A of mass m and initial velocity v collides with a particle B of mass \cfrac{m}{2} which is at rest. The collision is head on, and elastic. The ratio of the de-Broglie wavelengths { \lambda  }_{ A } and { \lambda  }_{ B } after the collision is :
  • \cfrac { { \lambda }_{ A } }{ { \lambda }_{ B } } =\cfrac { 1 }{ 2 }
  • \cfrac { { \lambda }_{ A } }{ { \lambda }_{ B } } =\cfrac { 1 }{ 3 }
  • \cfrac { { \lambda }_{ A } }{ { \lambda }_{ B } } =2
  • \cfrac { { \lambda }_{ A } }{ { \lambda }_{ B } } =\cfrac { 2 }{ 3 }
0:0:2


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 12 Medical Physics Quiz Questions and Answers