JEE Questions for Physics Dual Nature Of Radiation And Matter Quiz 4 - MCQExams.com

A and B are two metals with threshold frequencies 1.8 × 1014 Hz and 2.2 × 1014 Hz. Two identical photons of energy 0.825 eV each are incident on them. Then, photoelectrons are emitted by (take, h = 10-34 J-s )
  • B alone
  • A alone
  • Neither A nor B
  • Both A and B
In an experiment on photoelectric emission from a metallic surface, wavelength of incident light is 2 × 10-7 m and stopping potential is 2.5 V. The threshold frequency of the metal (in Hz) approximately (charge of electron, e = 1.6 × 10-19 C, Planck's constant, h = 6.6 × 10-34J-s)
  • 12 × 1015
  • 9 × 1015
  • 9 × 1014
  • 12 × 1013
Light of wavelength 5000 Å is falling on a sensitive surface. If the surface has received 10-7 J of energy, then the number of photons falling on the surface will be
  • 5 × 1011
  • 2.5 × 1011
  • 3 × 1011
  • None of these
The threshold frequency for a metallic surface corresponds to an energy of 6.2 eV and the stopping potential for a radiation incident on this surface is 5V. The incident radiation lies in
  • ultraviolet region
  • infrared region
  • visible region
  • X-rays region
The specific charge of a proton is 9.6 × 107 C kg-1 . The specific charge of an alpha particle will be
  • 9.6 × 107 C kg-1
  • 19.2 × 107 C kg-1
  • 4.8 × 107 C kg-1
  • 2.4 × 107 C kg-1
Threshold wavelength for photoelectric emission from a metal surface is 5200 Å . Photoelectrons will emitted when this surface is illuminated with monochromatic radiation from
  • 1 W infrared lamp
  • 50 W ultraviolet lamp
  • 50 W infrared lamp
  • 10 W infrared lamp
The photoelectric threshold frequency of a metal is v. When light of frequency 4v is incident on the metal. The maximum kinetic energy of the emitted photoelectrons is
  • 4 hv
  • 3 hv
  • 5 hv
  • 5/2 hv
In photoelectric effect, the number of electrons ejected per sec is
  • proportional to the wavelength of light
  • proportional to the intensity of light
  • proportional to the work function of the metal
  • proportional to the frequency of light
If the frequency of light incident on metal surface is doubled, then kinetic energy of emitted electron will become
  • doubled
  • less than double
  • more than double
  • Nothing can be said
Cathode ray is
  • a beam of atoms moving towards cathode
  • electromagnetic waves
  • a beam of negatively charged ions moving towards anode
  • a beam of electrons emitted by cathode.
Thermions are
  • protons
  • electrons
  • photons
  • positrons
Photo electric effect shows
  • wave like behaviour of light
  • particle like behaviour of light
  • both wave like and particle like behaviour of light
  • neither wavelike nor particle like behaviour of light
Which of the following is correct?
  • The current in a photocell increases with increasing frequency
  • The photocurrent is proportional to the applied voltage
  • The stopping potential increases with the intensity of light
  • The photocurrent increase with the intensity of light.
Photoelectrons are emitted when
  • zinc plate is hammered
  • zinc plate is heated
  • zinc plate is irradiated with light
  • zinc plate is subjected to very high pressure.
50% of X – rays obtained from a Coolidge tube pass through 0.3 mm thick aluminium foil. If the potential difference between the target and the cathode is increased, then the fraction of X – rays passing through the same foil will be
  • 50%
  • > 50%
  • < 50%
  • not sure
Stopping potential for photoelectrons
  • does not depend on the frequency of the incident light
  • does not depend upon the nature of the cathode material
  • depends on both the frequency of the incident light and the nature of cathode material
  • depends upon the intensity of the incident light.
Which of the following electromagnetic waves has minimum frequency ?
  • Radio wave
  • Ultrasonic wave
  • Microwave wave
  • Audiable wave
On increasing the number of electrons striking the anode of an X – ray tube, which one of the following parameters of the resulting X – rays would increase
  • penetration power
  • frequency
  • wavelength
  • intensity
A electron states from rest in an electric field and acquires a speed u in reaching a point A. The potential difference between the starting point and the point A is VA, then

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    Physics-Dual Nature of Radiation and Matter-67394.png

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When a proton is accelerated through 1 V, then its kinetic energy will be
  • 1840 eV
  • 13.6 eV
  • 1 eV
  • 0.54 eV
The slope of frequency of incident light and stopping potential for a given surface will be
  • h
  • h/e
  • eh
  • e
Proton and α − particle have the same de – Broglie wavelength. What is the same for both of them ?
  • Time period
  • Energy
  • Frequency
  • Momentum
Which of the following is not the property of cathode rays:
  • It produces the heating effect
  • It does not deflect in electric field
  • It casts shadow
  • It produces fluorescence
The frequency and work function of an incident photon are υ φ and 0. If v0 is the threshold frequency, then necessary condition for the emission of photoelectron is
  • v < v0
  • v = v0/2
  • v ≥ v0
  • none of these
Particle nature is shown by
  • Diffraction
  • Photoelectric effect
  • Polarization
  • TIR
According to Einstein’s photoelectric equation, the plot of the kinentic energy of the emitted photo electrons from a metal verses the frequency of the incident radiation gives a straight line whose slope
  • depends on the nature of the metal used
  • depends on the intensity of the radiation
  • depends both on the intensity of the radiation and metal used
  • is the same for all metals and is independent of the intensity of the radiation.
The magnitude of saturation photoelectric current depends upon
  • frequency
  • intensity
  • work function
  • stopping potential
The wavelength of matter wave is independent of
  • mass
  • velocity
  • momentum
  • charge
An image of sun is formed by a lens of focal length 30 cm on the metal surface of a photo-electric cell and a photoelectric current (I) is produced. The lens forming the image is then replaced by another of the same diameter but of focal length of 15 cm. The photoelectric current in this case is...............
  • 1/2
  • 1
  • 2I
  • 4I

Physics-Dual Nature of Radiation and Matter-67401.png
  • 1.6 × 10-19 C
  • 3.2 × 10-19 C
  • 4.8 × 10-19 C
  • 8.0 × 10-19 C
An uniform electric field and a uniform magnetic field exist in a region in the same direction. An electron is projected with a velocity pointed in the same direction. Then, the electron will
  • he deflected to the left without increase in speed
  • he deflected to the right without increase in speed
  • not be deflected but its speed will decrease
  • not be deflected but its speed will increase
  • be deflected to the right with increase in speed
Energy from the sun is received on the earth at the rate of 2 cal/cm2/min. If average wavelength of solar light be taken at 5500 Å, then how many photons are received on the earth per cm2 per min ?
(take, h = 6.6 × 10-34 J -s, 1cal = 4.2 J ) .
  • 1.5 × 1013
  • 2.9 × 1013
  • 2.3 × 1019
  • 1.75 × 1019
Which one of the following statement is wrong in the context of X–rays generated from X–ray tube ?
  • Wavelength of characteristic X–rays decreases when the atomic number of the target increases
  • Cut-off wavelength of the continuous X–rays depends on the atomic number of the target
  • Intensity of the characteristic X-rays depends on the electrical power given to the X–ray tube
  • Cut-off wavelength of the continuous X-rays depends on the energy of the electrons in the X–ray tube
Assertion (A) If the accelerating potential in an X-ray tube is increased, the wavelengths of the characteristic X-rays do not change.
Reason (R) When an electron beam strikes the target in an X-ray tube, part of the kinetic energy is converted into X-rays energy.
  • A is correct, R is correct R is a correct explanation for A
  • A is correct, R is correct R is not a correct explanation for A
  • A is correct, R is incorrect
  • A is incorrect, R is correct
A metal surface is illuminated by light of two different wavelengths 248 nm and 310 nm. The maximum speeds of the photoelectrons corresponding to these wavelengths are u1 and u2, respectively, If the ratio u1 : u2 = 2 : 1 and hc = 1240 eV nm, the work function of the metal is nearly
  • 3.7 eV
  • 3.2 eV
  • 2.8 eV
  • 2.5 eV
Find the incorrect statement(s) about photoelectric effect.
  • There is no significant time delay between the absorption of a suitable radiation and the emission of electrons
  • Einstein analysis gives a threshold frequency above which no electron can be emitted
  • The maximum kinetic energy of the emitted photoelectrons is proportional to the frequency of incident radiation
  • The maximum kinetic energy of electrons does not depend on the intensity of radiation

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    Physics-Dual Nature of Radiation and Matter-67405.png

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A photosensitive metallic surface has work function ϕ .If photon of energy 3 ϕfall on this surface, the electron comes out with a maximum velocity of 6 × 106 m/s. When the photon energy is increased to 9 ϕ, then maximum velocity of photoelectron will be
  • 12 × 106 m/s
  • 6 × 106 m/s
  • 3 × 106 m/s
  • 24 × 106 m/s
Assertion (A) 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.
Reason (R) Photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light.
  • If both A and R are correct and R is the correct explanation of A.
  • If both A and reason are correct but R is not the correct explanation of A.
  • If A is correct but R is incorrect.
  • If A is incorrect but R is correct.
According to Einstein's photoelectric equation, the graph of KE of the photoelectron emitted from the metal versus the frequency of the incident radiation gives a straight line graph, whose slope
  • depends on the intensity of the incident radiation
  • depends on the nature of the metal and also on the intensity of incident radiation
  • is same for all metals and independent of the intensity of the incident radiation
  • depends on the nature of the metal
In photoelectric experiment, the relation between applied potential difference between cathode and anode V and the photoelectric current I was found to be shown in the graph below If Planck's constant h = 6.6 × 10-34 J-s , the frequency of incident radiation would be nearly (in s-1 )
Physics-Dual Nature of Radiation and Matter-67408.png
  • 0.436 × 1018
  • 0.436 × 1017
  • 0.775 × 1015
  • 0.775 × 1016
Figure represents a graph of kinetic energy of most energetic photoelectrons, Kmax (in eV) and frequencry (v) for a metal used as cathode in photoelectric experiment. The threshold frequency of light for the photoelectric emission from the metal is
Physics-Dual Nature of Radiation and Matter-67409.png
  • 1 × 1014 Hz
  • 1.5 × 1014 Hz
  • 2.1 × 1014 Hz
  • 2.7 × 1014 Hz
The figure shows variation of photocurrent with anode potential for a photosensitive surface for three different radiations. Let Ia , Ib and Ic be the intensities and va , vb and vc be the frequencies for the curves a, b and c respectively. Then,
Physics-Dual Nature of Radiation and Matter-67410.png
  • va = vb and Ia ≠ Ib
  • va = vc and Ia = Ic
  • va = vb and Ia < Ib
  • vb = vc and Ib = Ic
When a monochromatic point source of light is at distance 0.2 m from a photoelectric cell, the saturation current and cut-off voltage are 12.0 mA and 0.5 V. If the. same source is placed 0.4 m away from the photoelectric cell, then the saturation current and the stopping potential respectively are
  • 4 mA and 1 V
  • 12 mA and 1 V
  • 3 mA and 1 V
  • 12 mA and 0.5 V
  • 3 mA and 0.5 V
A 5 W source emits monochromatic light of wavelength 5000 Å . When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0 m, the number of photoelectrons liberated will be reduced by a factor of
  • 4
  • 8
  • 16
  • 2
Stopping potential required to reduce the photoelectric current to zero
  • is directly proportional to the wavelength of the incident radiation
  • increases uniformly with wavelength of the incident radiation
  • is directly proportional to the frequency of the incident radiation
  • decreases uniformly with the frequency of the incident radiation
From the figure, describing photoelectric effect we may infer correctly that
Physics-Dual Nature of Radiation and Matter-67411.png
  • Na and Al both have the same threshold frequency
  • maximum kinetic energy for both the metals depend linearly on the frequency
  • the stopping potentials are different for Na and Al for the same change in frequency
  • Al is a better photo sensitive material than Na
In Bainbridge mass spectrograph, the ion C12 strikes the photograph plate at a distance of 12 cm from the slit. At what distance from the slit will be ion C14 strike?
  • 1.4 cm
  • 0.14 m
  • 14 m
  • 7 cm
Planck’s constant has the dimensions of
  • Energy
  • Mass
  • Frequency
  • Angular momentum
Energy of a photon can not be represented by

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    Physics-Dual Nature of Radiation and Matter-67415.png

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