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

The kinetic energy of electron and proton is $$10^{-32}\ J$$. Then the relation between their de-Broglie wavelength is 
  • $$\lambda_p < \lambda_e$$
  • $$\lambda_p > \lambda_e$$
  • $$\lambda_p = \lambda_e$$
  • $$\lambda_p =2 \lambda_e$$
AN important spectral emission line has a wavelength of $$21\ cm$$. The corresponding photon energy is
  • $$5.9\times 10^{-4}eV$$
  • $$5.9\times 10^{-6}eV$$
  • $$5.9\times 10^{-8}eV$$
  • $$11.8\times 10^{-6}eV$$
Which of the following is true for photon
  • $$E=\dfrac {hc}{\lambda}$$
  • $$E=\dfrac {1}{2}mu^2$$
  • $$p=\dfrac {E}{2v}$$
  • $$E=\dfrac {1}{2}mc^2$$
The de-Broglie wavelength is proportional to 
  • $$\lambda \propto \dfrac 1v$$
  • $$\lambda \propto \dfrac 1m$$
  • $$\lambda \propto \dfrac 1p$$
  • $$\lambda \propto p$$
The spectrum of radiation $$1.0\times 10^{14}Hz$$ is the infrared region. The energy of one photon of this in joules will be
  • $$6.62\times 10^{-48}$$
  • $$6.62\times 10^{-20}$$
  • $$\dfrac {6.62}{3}\times 10^{-28}$$
  • $$3\times 6.62\times 10^{-28}$$
A laser is a coherent source because it contains
  • Many wavelengths
  • Unconditinated wave of a particular wavelength
  • Coordinated wave of many wavelengths
  • Coordinated wave of particular wavelengths
The minimum wavelength of photons is $$5000 \overset {o}{A}$$, its energy will be 
  • $$2.5\ eV$$
  • $$50\ eV$$
  • $$5.48\ eV$$
  • $$7.48\ eV$$
If the energy of a photon correspoiding to a wavelength of $$6000\overset {o}{A}$$ is $$3.32\times 10^{-19}J$$, the photon energy for a wavelength of $$4000\overset {o}{A}$$ will be
  • $$1.4\ eV$$
  • $$4.9\ eV$$
  • $$3.1\ eV$$
  • $$1.6\ eV$$
de-Broglie wavelength of a body of mass $$m$$ and kinetic energy $$E$$ is given by 
  • $$\lambda =\dfrac {h}{mE}$$
  • $$\lambda =\dfrac {\sqrt{2mE}}{h}$$
  • $$\lambda =\dfrac {h}{2mE}$$
  • $$\lambda =\dfrac {h}{\sqrt{2mE}}$$
A proton and an $$\alpha$$ particle are acclerated through a potential difference of $$100\ V$$. The ratio of the wavelength associated with the proton to that associated with an $$\alpha$$- particle is 
  • $$\sqrt 2:1$$
  • $$2:1$$
  • $$2\sqrt 2:1$$
  • $$\dfrac{1}{2\sqrt 2}:1$$
The log-log graph between the energy $$E$$ of an electron and its de-Broglie wavelength $$\lambda$$ will be
For moving ball of cricket, the correct statement about de-Broglie wavelength is 
  • It is not applicable for such big particle
  • $$\dfrac{h}{\sqrt{2mE}}$$
  • $$\sqrt{\dfrac{h}{2mE}}$$
  • $$\dfrac{h}{2mE}$$
An electron is moving through a field. It is moving (i) opposite an electric field (ii) perpendicular to a magnetic field as shown. For each situation the de-Broglie wave length of electron
1818527_ca2edb846723479eb6041b12e5edc099.png
  • Increasing, Increasing
  • Increasing,decreasing
  • Decreasing, same
  • same,same
Find out the de-Broglie wavelength related to an electron of kinetic energy $$10$$ eV:
  • $$10 \mathring A $$
  • $$ 1227 \mathring A $$
  • $$ 0.10 \mathring A $$
  • $$ 3.9 \mathring A $$
The output from a LASER is monochromatic. It means that it is
  • Directional
  • Polarised
  • Narrow beam
  • Single frequency
Given below are two statements:
Statement I: Two photons having equal linear momenta have equal wavelengths.
Statement- II: If the wavelength of photon is decreased, then the momentum and energy of a photon will also decrease. 
In the light of the above statements, choose the correct answer from the options given below. 
  • Both Statement I and Statement II are true.
  • Statement I is false but Statement II is true
  • Both Statement I and Statement II are false
  • Statement I is true but Statement II is false
The wavelength of the de-Broglie wave associated with a thermal neutron of mass $$m$$ at absolute temperature $$T$$ is given by: 
($$k$$ is the Boltzmann constant)
  • $$\displaystyle \frac{h}{\sqrt{mkT}}$$
  • $$\displaystyle \frac{h}{\sqrt{2mkT}}$$
  • $$\displaystyle \frac{h}{\sqrt{3mkT}}$$
  • $$\displaystyle \frac{h}{2\sqrt{mkT}}$$
What should be the approximate K.E. of an electron so that its de -Broglie wavelength is equal to the wavelength of x -ray of maximum energy produced in an x -ray tube operating at 24,800 V? $$(h = 6.6 /\times 10^{-34}J - sec$$, mass of electron $$m =9.1 \times 10^{-31} kg)$$ (give answer in $$10^2 eV).$$
  • $$3$$
  • $$4$$
  • $$6$$
  • $$9$$
Photoelectrons emitted from a photo sensitive metal of work function $$1eV$$ describe a circle of radius 0.1 cm in a magnetic field of induction $$10^{-3}$$ Tesla. The energy of the incident photons is (mass of electron $$= 9 \times 10^{-31}$$kg)
  • $$1.17 eV$$
  • $$2.9 eV$$
  • $$0.9 eV$$
  • $$0.81 eV$$
A proton is fired from very far away towards a nucleus with charge Q = 120 e, where e is the electronic charge. It makes a closest approach of 10 fm to the nucleus. The de Broglie wavelength (in units of fm) of the proton at its start is :

 (take the proton mass, $$m_p = (5/3) \times 10^{-27}kg$$ and

$$h/e = 4.2\times 10^{-15}J.s/C; \frac{1}{4\pi\epsilon_0} = 9 \times 10^9 m/F; 1 fm = 10^{-15}m$$)
  • $$7\ fm$$
  • $$8\ fm$$
  • $$9\ fm$$
  • $$10\ fm$$
The light of radiation $$300 nm$$ falls on a photocell operating in the saturation mode. The spectral sensitivity is $$4.8 mA/W.$$ The yield of photo electrons (i.e. number of electrons produced per photon) is
  • $$0.04$$
  • $$0.02$$
  • $$0.03$$
  • $$0.2$$
The de-Broglie wavelength of a neutron at $$927^{0}$$C is$$\lambda$$. Its wavelength at $$27^{0}$$C is:
  • $$\dfrac{\lambda}{2}$$
  • $$\lambda$$
  • $$2\lambda$$
  • $$4\lambda$$
Choose the correct statements from the following about photoelectric emission
  • For given emitter illuminated by light of a given frequency, the number of photoelectrons emitted per second is proportional to the intensity of incident light
  • For every emitter there is a definite threshold frequency below which no photo electrons are emitted, no matter what the intensity of light is
  • Above the threshold frequency, the maximum kinetic energy of photo electrons is proportional to the frequency of incident light
  • The saturation value of the photoelectric current is independent of the intensity of incident light
When photons of energy $$4.25 eV$$ strike the surface of a metal A, the ejected photoelectrons have maximum kinetic energy of $$K_{A}$$ eV and de Broglie wavelength $$\lambda_{A}$$. The maximum kinetic energy of photo electrons liberated from another metal B by photons of energy $$4.70 eV$$ is $$K_{B}=(K_{A}-1.5) eV$$. If the de Broglie wavelength of these photoelectrons is $$\lambda _{B}=2\lambda _{A}$$ then
  • the work function of A is 2.25 eV
  • the work function of B is 4.20 eV
  • $$K_{A}=2.00$$ eV
  • $$K_{B}=2.75$$ eV
Select correct alternative :
Statement -1 : An electric dipole can not produce zero electric field at a point which is situated at finite distance from the dipole.
Statement -2 : Mass of a moving photon is proportional to $$ \lambda^{-1} $$ .
Statement -3 : Equation of continuity for fluid is based on conservation of volume.
  • FFF
  • TTF
  • TFF
  • TTT
The number of photons emitted per second by a $$40 $$W lamp, if $$15 \% $$ of the energy appears as the radiation of wavelength 540 $$\mathrm { nm }$$ is
  • $$1.63 \times 10 ^ { 19 } $$
  • $$1.5 \times 10 ^ { 10 } $$
  • $$2.2 \times 10 ^ { 10 } $$
  • $$1.63 \times 10 ^ { 18 } $$
A photosensitive metallic surface has work function, h $$_{0}$$. If photons of energy 2h $$_{0}$$ fall on this surface, the electrons come out with a maximum velocity of 4 10$$^{6}$$ m/s. When the photon energy is increased to 5h$$_{0}$$, then maximum velocity of photo electrons will be
  • 2 10$$^{7}$$ m/s
  • 2 10$$^{6}$$ m/s
  • 8 10$$^{5}$$ m/s
  • 8 10$$^{6}$$ m/s
A point source of light of power $$P$$ and wavelength $$\lambda$$ is emitting light in all directions. The number of photons present in a spherical region of radius $$r$$ to radius $$r+x$$ with centre at the source is:
  • $$\dfrac{P\lambda}{4 \pi r^2 hc}$$
  • $$\dfrac{P\lambda x}{hc^2}$$
  • $$\dfrac{P\lambda x}{4 \pi r^2 hc}$$
  • None of these
A charge particle $$q_0$$ of mass $$m_0$$ is projected along the y-axis at $$t = 0$$ from origin with a velocity $$V_0.$$ If a uniform electric field $$E_0$$ also exists along the x-axis, then the time at which de Broglie wavelength of the particle becomes half of the initial value is :
  • $$\dfrac{m_{0}v_{0}}{q_{0}E_{0}}$$
  • $$2\dfrac{m_{0}v_{0}}{q_{0}E_{0}}$$
  • $$\sqrt3\dfrac{m_{0}v_{0}}{q_{0}E_{0}}$$
  • $$3\dfrac{m_{0}v_{0}}{q_{0}E_{0}}$$
A particle of mass $$'m\ '$$ is projected from ground with velocity $$'u\ '$$ making an angle $$'\theta \ '$$ with the vertical. The de-Broglie wavelength of the particle at the highest point is 
  • $$\infty$$
  • $$\dfrac{h}{mu sin \theta}$$
  • $$\dfrac{h}{mu cos \theta}$$
  • $$\dfrac{h}{mu}$$
If the shortest wavelength of the continuous X-ray spectrum coming out of a Coolidge tube is $$0.01nm$$, then the de Broglie wavelength of the electron reaching the target metal in the Coolidge tube is approximately
$$ (hc = 12400 e VA, h = 6.63 \times 10^{-34} $$ in  MKS, mass  of  electron$$  = 9.1 \times 10^{-31}kg)$$
  • $$0.35$$
  • $$0.035$$
  • $$35$$
  • $$1350$$
A small 50 kg vehicle is designed to be moved in free space by a lamp which emits 100 watts of red light of $$\lambda = 6630  A^o$$. What is its acceleration?
  • $$6.66 \times 10^{-9}\ m/sec^{2}$$
  • $$3 \times 10^{-9}\ m/sec^{2}$$
  • $$2.22 \times 10^{-9}\ m/sec^{2}$$
  • $$4.44\ m/sec^{2}$$
A photon of frequency v has an energy
  • $$\frac {h}{v}$$
  • $$\frac {v}{h}$$
  • v
  • hv
If a hydrogen atom at rest, emits a photon of wavelength $$\lambda ,$$ the recoil speed of the atom of mass $$'m'$$ is given by 
  • $$\dfrac{h}{m\lambda }$$
  • $$\dfrac{mh }{\lambda }$$
  • $$mh\lambda $$
  • none of these
Photoelectric effect is described as the ejection of electrons from the surface of metal when
  • It is heated to high temperature
  • Light of suitable wavelength falls on it
  • Electrons of a suitable velocity impinge on it
  • It is placed in a strong magnetic field
Photoelectric effect can be explained only by assuming that
  • Light is a form of transverse waves
  • Light is a form of longitudinal waves
  • Light can be polarised
  • Light consists of quanta
A light of wavelength $$ \lambda$$ is incident on a metal sheet of work function $$ \phi = 2eV$$. The  wavelength $$ \lambda$$ varies with time as $$ \lambda = 3000 + 40t,   where   \lambda$$ is in and t is in second. The power incident on metal sheet is constant at 100 W. This signal is switched on and off for time intervals of 2 minutes and 1 minute respectively. Each time the signal is switched on, the $$ \lambda$$ start from an initial value of 3000. The metal plate is grounded and electron clouding is negligible. The efficiency of photoemission is 1%$$ (hc = 12400 eV)$$. The time after which photo-emission will stop is 
  • 79 s
  • 80 s
  • 81 s
  • 78 s
A proton and an electron are accelerated by the same potential difference. Let $$\lambda _{e}$$ and $$\lambda _{p}$$ denote the de Broglie wavelengths of the electron and the proton respectively.
  • $$\lambda _{e}=\lambda _{p}$$
  • $$\lambda _{e}< \lambda _{p}$$
  • $$\lambda _{e}> \lambda _{p}$$
  • $$\lambda _{e}$$ and $$\lambda _{p}$$ depend on the accelerating potential difference.
If the shortest wavelength of the continuous X-ray spectrum coming out of a Coolidge tube is $$0.1\mathring{A}$$, then the de Broglie wavelength of the electron reaching the target metal in the Coolidge tube is approximately 
($$hc=12400eV\mathring{A}$$, $$h=6.63\times{10}^{-34}$$ in MKS, mass of electron $$=9.1\times{10}^{-31}kg$$)
  • $$0.35\mathring{A}$$
  • $$0.035\mathring{A}$$
  • $$35\mathring{A}$$
  • $$3.5\mathring{A}$$
If we assume that penetrating power of any radiation/particle is inversely proportional to the De-broglie wavelength of the particle, then
  • A proton and an $$\alpha-$$particle after getting accelerated through same potential difference will have equal penetrating power.
  • Penetrating power of $$\alpha-$$particle will be greater than that of proton which have been accelerated by same potential difference.
  • Proton's penetrating power will be less than penetrating power of an electron which has been accelerated by the same potential difference.
  • Penetrating powers can not be compared as all these are particles having no wavelength or wave nature.
A photon of frequency v has a momentum associated with it. If c is the velocity of light, then momentum is
  • $$\frac {hv}{c^2}$$
  • $$\frac {hv}{c}$$
  • $$\frac {v}{c}$$
  • $$h vc$$
A photon is an
  • Quantum of light energy
  • Quantum of matter
  • Positively charged particle
  • instrument for measuring light intensity
Two particles of masses $$m$$ and $$2m$$ have equal kinetic energies. Their de Broglie wavelengths are in the ratio of :
  • $$1 : 1$$
  • $$1 : 2$$
  • $$1:\sqrt{2}$$
  • $$\sqrt{2}:1$$
Will the radiation from a 50 kW, 100 MHz FM station expose the film?
  • No
  • Yes
  • Cannot Say
  • Incomplete data
The idea of quantum nature of light has emerged in an attempt to explain
  • The thermal radiation of a black body
  • The interference of light
  • Radioactivity
  • Thermionic emission
Find the frequency of photon.
  • 2.71 $$\times$$ 10$$^{14}Hz$$
  • 2.01 $$\times$$ 10$$^{14}Hz$$
  • 2.5 $$\times$$ 10$$^{14}Hz$$
  • 20.1 $$\times$$ 10$$^{14}Hz$$
Mass of the photon at rest is
  • $$1.67\times 10^{-35} kg$$
  • One a.m.u
  • $$9\times 10^{-31} kg$$
  • Zero
de Broglie relation is true  for
  • All particles
  • Charged particles only
  • Negatively charged particles only
  • Massless particles like photons only
A ray of energy 14.2 Me V is emitted from a $$^{60}Co$$ nucleus. The recoil energy of the co-nucleus is nearly 
  • $$3 \times 10^{-10}J$$
  • $$3 \times 10^{-15}J$$
  • $$3 \times 10^{-14}J$$
  • $$3 \times 10^{-13}J$$
A  proton and an electron are accelerated by the same potential difference. Let $$\displaystyle \lambda _{c}$$ and $$\displaystyle \lambda _{p}$$ denote the de Broglie wavelengths of the electron and the proton respectively.
  • $$\displaystyle \lambda _{c}= \lambda _{p}$$
  • $$\displaystyle \lambda _{c}< \lambda _{p}$$
  • $$\displaystyle \lambda _{c}> \lambda _{p}$$
  • The relation between $$\displaystyle \lambda _{c}$$ and $$\displaystyle \lambda _{p}$$ depends on the accelerating potential difference.
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 12 Medical Physics Quiz Questions and Answers