JEE Questions for Physics Dual Nature Of Radiation And Matter Quiz 14 - MCQExams.com

The graph between 1 / λ and stopping potential (V) of three metals having work functions ϕ1, ϕ2 and ϕ3 in an experiment of photo-electric effect is plotted as shown in the figure. Which of the following statement(s) is/are correct? [Here λ is the wavelength of the incident ray]
Physics-Dual Nature of Radiation and Matter-68070.png
  • Ratio of work functions ϕ1 : ϕ2 : ϕ3 = 1 : 2 : 4
  • Ratio of work functions ϕ1 : ϕ2 : ϕ3 = 4 : 2 : 1
  • tan θ is directly proportional to he /e, where h is Planck's constant and c is the speed of light
  • The violet colour light can eject photoelectrons from metals 2 and 3
Einstein\'s photoelectric equation states that Ek = hv–ɸ). In this equation Ekrefers to
  • Kinetic energy of all the emitted electrons
  • Mean kinetic energy of the emitted electrons
  • Maximum kinetic energy of the emitted electrons
  • Minimum kinetic energy of the emitted electrons
When photon of energy 4.25 eV strike the surface of a metal A, the ejected photoelectrons have maximum kinetic energy TA eV and de-Broglie wavelength λA. The maximum kinetic energy of photoelectrons liberated from another metal B by photon of energy 4.70 eV is TB = (TA – 1.eV. If the de-Broglie wavelength of these photoelectrons is λB = 2λA, then
  • The work function of A is 2.25 eV
  • The work function of B is 4.20 eV
  • TA = 2.00 eV
  • TB = 2.75 eV
The potential difference applied to a X-ray tube is increased. As a result, in the emitted radiation
  • The intensity wavelength increases
  • The minimum wavelength increases
  • The intensity remains unchanged
  • The minimum wavelength decreases
Photoelectric effect support quantum nature of light because
  • There is a minimum frequency of light below which no photoelectrons are emitted
  • The maximum kinetic energy of photoelectrons depends only on the frequency of light and not on its intensity
  • Even when the metal surface is faintly illuminated, the photoelectrons leave the surface immediately
  • Electric charge of the photoelectrons is quantized
The threshold wavelength, for photoelectric emission, from a material is 5200 Å. Photoelectrons will be emitted when this material is illuminated with monochromatic radiation from a
  • 50 watt infrared lamp
  • 1 watt infrared lamp
  • 50 watt ultraviolet lamp
  • 1 watt ultraviolet lamp
The shortest wavelength of X-rays emitted from an X-ray tube depends on
  • The current in the tube
  • The voltage applied to the tube
  • The nature of the gas in the tube
  • The atomic number of the target material
An X-ray tube is operating at 50 kV and 20 mA. The target material of the tube has a mass of 1.0 kg and specific heat 495 J kg–1° C–1. One percent of the supplied electric power is converted into X-rays and the entire remaining energy goes into heating the target. Then
  • A suitable target material must have a high melting temperature
  • A suitable target material must have low thermal conductivity
  • The average rate of rise of temperature of target would be 2°C/s
  • The minimum wavelength of the X-rays emitted is about 0.25 × 10–10 m
Statement I If the accelerating potential in a X-ray tube is increased, the wavelengths of the characteristic X-rays do not change
Statement II When an electron beam strikes the target in an X-ray tube, part of the kinetic energy is converted into X-ray energy
  • Statement I is true, statement II is true; statement II is a correct explanation for statement I
  • Statement I is true, statement II is true; statement II is not a correct explanation for statement I
  • Statement I is true, statement II is false
  • Statement I is false, statement II is true
Statement I When ultraviolet light is incident on a photocell, its stopping potential is V0 and the maximum kinetic energy of the photoelectrons is Kmax. When the ultraviolet light is replaced by X-rays, both V0 and Kmax increase.
Statement II Photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light.
  • Statement I is true, statement II is true; statement II is a correct explanation for statement I
  • Statement I is true, statement II is true; statement II is not a correct explanation for statement I
  • Statement I is true, statement II is false
  • Statement I is false, statement II is true
Statement I A metallic surface is irradiated by a monochromatic light of frequency v > v0 (the threshold frequency). The maximum kinetic energy and the stopping potential are Kmax and V0 respectively. If the frequency incident on the surface is doubled, both the Kmax and V0 are also doubled.
Statement II The maximum kinetic energy and the stopping potential of photoelectrons emitted from a surface are linearly dependent on the frequency of incident light.
  • Statement I is true, statement II is true; statement II is a correct explanation for statement I
  • Statement I is true, statement II is true; statement II is not a correct explanation for statement I
  • Statement I is true, statement II is false
  • Statement I is false, statement II is true
Wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electrons waves reflected from the planes of atoms in a crystal interfere constructively (see figure).
If a strong diffraction peak is observed when electrons are incident at an angle \'1\' from the normal to the crystal planes with distance \'d\' between them (see figure), de-Broglie wavelength λdB of electrons can be calculated by the relationship (n is an integer)
Physics-Dual Nature of Radiation and Matter-68078.png
  • 2d cos i = n λdB
  • 2d sin i = n λdB
  • d cosi = n λdB
  • d sin i = n λdB
Wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electrons waves reflected from the planes of atoms in a crystal interfere constructively (see figure).
Electrons accelerated by potential V are diffracted from a crystal. If d = 1 Å and i = 30° , V should be about
(h = 6.6 × 10–34 Js, me = 9.1 × 10–31kg, e = 1.6 × 10–19C)
Physics-Dual Nature of Radiation and Matter-68080.png
  • 50 V
  • 500 V
  • 1000 V
  • 2000 V

Physics-Dual Nature of Radiation and Matter-68082.png

  • Physics-Dual Nature of Radiation and Matter-68083.png
  • 2)
    Physics-Dual Nature of Radiation and Matter-68084.png

  • Physics-Dual Nature of Radiation and Matter-68085.png

  • Physics-Dual Nature of Radiation and Matter-68086.png
A dense collection of equal number of electrons and positive ions is called neutral plasma. Certain solids containing fixed positive ions surrounded by free electrons can be treated as neutral plasma. Let \'N\' be the number density of free electrons, each of mass \'m\'. When the electrons are subjected to an electric field, they are displaced relatively away from the heavy positive ions. If the electric field becomes zero, the electrons begin to oscillate about the positive ions with a natural angular frequency ‘ωp\', which is called the plasma frequency. To sustain the oscillations, a time varying electric field needs to be applied that has an angular frequency ω, where a part of the energy is absorbed and a part of it is reflected. As ω approaches ωp all the free electrons are set to resonance together and all the energy is reflected. This is the explanation of high reflectivity of metals.
Taking the electronic charge as ‘e\' and the permittivity as \'ε0\', use dimensional analysis to determine the correct expression for ωp

  • Physics-Dual Nature of Radiation and Matter-68088.png
  • 2)
    Physics-Dual Nature of Radiation and Matter-68089.png

  • Physics-Dual Nature of Radiation and Matter-68090.png

  • Physics-Dual Nature of Radiation and Matter-68091.png
A dense collection of equal number of electrons and positive ions is called neutral plasma. Certain solids containing fixed positive ions surrounded by free electrons can be treated as neutral plasma. Let \'N\' be the number density of free electrons, each of mass \'m\'. When the electrons are subjected to an electric field, they are displaced relatively away from the heavy positive ions. If the electric field becomes zero, the electrons begin to oscillate about the positive ions with a natural angular frequency ‘ωp\', which is called the plasma frequency. To sustain the oscillations, a time varying electric field needs to be applied that has an angular frequency ω, where a part of the energy is absorbed and a part of it is reflected. As ω approaches ωp all the free electrons are set to resonance together and all the energy is reflected. This is the explanation of high reflectivity of metals.
Estimate the wavelength at which plasma reflection will occur for a metal having the density of electrons N = 4 × 1027 m–3. Take ε0 = 10–11 and m = 10–30, where these quantities are in proper SI units
  • 800 nm
  • 600 nm
  • 300 nm
  • 200 nm
A silver sphere of radius 1 cm and work function 4.7 eV is suspended from an insulating thread in free-space. It is under continuous illumination of 200 nm wavelength light. As photoelectrons are emitted, the sphere gets charged and acquires a potential. The maximum number of photoelectrons emitted from the sphere is A × 10Z (where 1 < A < 10). The value of ‘Z’ is
  • 7
  • 5
  • 12
  • 1

Physics-Dual Nature of Radiation and Matter-68095.png
  • 7
  • 5
  • 12
  • 1
When light falls on a metal surface, the maximum kinetic energy of the emitted photo-electrons depends upon
  • The time for which light falls on the metal
  • Frequency of the incident light
  • Intensity of the incident light
  • Velocity of the incident light
Some laws/processes are given in Column I. Match these with the physical phenomena given in Column II
Physics-Dual Nature of Radiation and Matter-68097.png
  • A→p,r ; B→q,s ; C→p ; D→q
  • A→q,r ; B→q,s ; C→p ; D→p
  • A→p,r ; B→q,s ; C→q ; D→p
  • A→q,s ; B→p,r ; C→p ; D→q
In the following, Column I lists some physical quantities and the Column II gives approximate energy values associated with some of them. Choose the appropriate value of energy from Column II for each of the physical quantities in Column I
Physics-Dual Nature of Radiation and Matter-68098.png
  • A→p ; B→t ; C→u ; D→r
  • A→r ; B→t ; C→u ; D→p
  • A→p ; B→u ; C→t ; D→r
  • A→p ; B→r ; C→u ; D→t
Assertion The energy (E) and momentum (p) of a photon are related by p = E /c.
Reason The photon behaves like a particle.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Photoelectric effect demonstrates the wave nature of light.
Reason The number of photoelectrons is proportional to the frequency of light.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion When the speed of an electron increases its specific charge decreases.
Reason Specific charge is the ratio of the charge to mass
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion X-rays travel with the speed of light.
Reason X-rays are electromagnetic rays.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
Assertion Mass of moving photon varies inversely as the wavelength.
Reason Energy of the particle = Mass × (Speed of light)2
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Kinetic energy of photo electrons emitted by a photosensitive surface depends upon the intensity of incident photon.
Reason The ejection of electrons from metallic surface is possible with frequency of incident photon below the threshold frequency.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true
Assertion Separation of isotope possible because of the difference in electron numbers of isotope.
Reason Isotope of an element can be separated by using a mass spectrometer
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion The specific charge of positive rays is not universal constant.
Reason The mass of ions varies with speed.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
Assertion Photo sensitivity of a metal is high if its work function is small.
Reason Work function = hf0, where f0 is the threshold frequency.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
Assertion The de-Broglie wavelength of a moelcule varies inversely as the square root of temperature.
Reason The root mean square velocity of the molecule depends on the temperature.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
Assertion An electron is not deflected on passing through certain region of space. This observation confirms that there is no magnetic field in that region.
Reason The deflection of electron depends on angle between velocity of electron and direction of magnetic field
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
Assertion Electric conduction in gases is possible at normal pressure.
Reason The electric conduction in gases depends only upon the potential difference between the electrodes.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Light is produced in gases in the process of electric discharge through them at high pressure.
Reason At high pressure electrons of gaseous atoms collide and reach an excited state.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion The photo electrons produced by a monochromatic light beam incident on a metal surface have a spread in their kinetic energies.
Reason The work function of the metal varies as a function of depth from the surface.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion An electric field is preferred in comparison to magnetic field for detecting the electron beam in a television picture tube.
Reason Electric field requires low voltage.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion The specific charge for positive rays is a characterisitc constant.
Reason The specific charge depends on charge and mass of positive ions present in positive rays.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion In Millikan\'s experiment for the determination of charge on an electron, oil drops of any size can be used.
Reason Millikan\'s experiment determines the charge on electron, by simply measuring the terminal velocity.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion In the process of photoelectric emission, all the emitted photoelectrons have the same kinetic energy.
Reason The photon transfers its whole energy to the electron of the atom in photoelectric effect.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
Five elements A, B, C, D and E have work function 1.2 eV, 2.4 eV, 3.6 eV, 4.8 eV and 6 eV respectively. If light of wavelength 4000 Å 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
A metal surface of work function 1.07 eV is irradiated with light of wavelength 332 nm. The retarding potential required to stop the escape of photo-electrons is
  • 4.81 V
  • 3.74 V
  • 2.66 V
  • 1.07 V
Assertion In photoelectric effect, on increasing the intensity of light, both the number of electrons emitted and kinetic energy of each of them get increased but photoelectric current remains unchanged.
Reason The photoelectric current depends only on wavelength of light.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
Assertion Standard optical diffraction can not be used for discriminating between different X-ray wavelengths.
Reason The grating spacing is not of the order of X-ray wavelengths
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion The threshold frequency of photoelectric effect supports the particle nature of sunlight.
Reason If frequency of incident light is less than the threshold frequency, electrons are not emitted from metal surface.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
Assertion In photoemissive cell inert gas is used.
Reason Inert gas in the photoemissive cell gives greater current.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion X-rays cannot be diffracted by means of grating.
Reason X-rays do not obey Bragg\'s law.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true
Assertion X-rays can penetrate through the flesh but not through the bones.
Reason The penetrating power of X-rays depends on voltage.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true
Assertion Intensity of X-rays can be controlled by adjusting the filament current and voltage.
Reason The intensity of X-rays does not depend on number of X-ray photons emitted per second from the target.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Soft and hard X-rays differ in frequency as well as velocity.
Reason The penetrating power of hard X-rays is more than the penetrating power of soft X-rays.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
Assertion Penetrating power of X-rays increases with the increasing the wavelength.
Reason The penetrating power of X-rays increases with the frequency of X-rays.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Physics Quiz Questions and Answers