Physics - Dual Nature Radiation Matter - Quiz-6

The stopping potential $(V_{0})$ versus frequency (v) plot of a substance is shown in figure. The threshold wavelength is-

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$5 \times 10^{14} m$
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6000 Å
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5000 Å
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can not be estimated from given data

The dependence of the short wavelength limit $λ_{\min}$ on the accelerating potential V is represented by the curve of figure:

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A
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B
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C
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None of these

The curves (a), (b) (c) and (d) show the variation between the applied potential difference (V) and the photoelectric current (i), at two different intensities of light ( $I_{1} > I_{2}$ ). In which figure is the correct variation shown ?

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1
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2
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3
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4

The photoelectric threshold wavelength of silver is 3250 x 10^-10m. The velocity of the electron ejected from a silver surface by the ultraviolet light of wavelength 2536 x 10^-10 m is:

(Given h= $4.14 \times 10^{- 15} eVs$ and $c = 3 \times 10^{8} {ms}^{- 1}$ )

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$\approx 0.6 \times 10^{6} m s^{- 1}$
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$\approx 61 \times 10^{3} m s^{- 1}$
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$\approx 0.3 \times 10^{6} m s^{- 1}$
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$\approx 0.3 \times 10^{5} m s^{- 1}$

A proton and an $α -$ particle are accelerated from rest to the same energy. The de-Broglie wavelength $λ_{p}$ and $λ_{α}$ are in the ratio:

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2:1
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1:1
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$\sqrt{2} : 1$
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4:1

When light of frequency 2 $ν$ _o (where $ν$ _o is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is $v_{1}$ . When the frequency of the incident radiation is increased to 5 $ν$ _o, the maximum velocity of electrons emitted from the same plate is $v_{2}$ . The ratio of $v_{1}$ to $v_{2}$ is

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1: 2
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1: 4
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4: 1
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2: 1

Radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (c = velocity of light) :

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$\frac{E}{c}$
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$\frac{2 E}{c}$
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$\frac{2 E}{c^{2}}$
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$\frac{E}{c^{2}}$

A certain metallic surface is illuminated with monochromatic light of wavelength

λ

.The stopping potential for photoelectric current for this light is 3V₀. If the same surface is illuminated with light of wavelength 2

λ

, the stopping potential is V₀. The threshold wavelength for this surface for the photoelectric effect is

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$6 λ$
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$4 λ$
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$\frac{λ}{4}$
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$\frac{λ}{6}$

Which of the following figures represent the variation of the particle momentum and the associated de-Broglie wavelength?

For photoelectric emission from certain metal, the cut off frequency is $ν$ . If radiation of frequency 2 $ν$ impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass):

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$\sqrt{hν / m}$
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$\sqrt{2 hν / m}$
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$2 \sqrt{hν / m}$
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$\sqrt{hν / (2 m)}$

In the photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV. The corresponding stopping potential is:

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1.3 V
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0.5 V
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2.3 V
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1.8 V

Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Ratio of maximum speeds of emitted electrons will be

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1:2
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1:1
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1:5
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1:4

Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 kV, then the de-Broglie wavelength associated with the electrons would

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decrease by 2 times
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decrease by 4 times
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increase by 4 times
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increase by 2 times

A source S₁ is producing, 10¹⁵ photons per sec of wavelength 5000. Another source S₂ is producing 1.02×10¹⁵ photons per second of wavelength 5100. Then, (power of S₂)/(power of S₁) is equal to

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1.00
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1.02
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1.04
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0.98

Monochromatic light of wavelength 667 nm is produced by a helium-neon laser. The power emitted is 9mW. The number of photons arriving per second on an average at a target irradiated by this beam are

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9 x 10¹⁷
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3 X 10¹⁶

9 x 10¹⁵

The number of photoelectrons emitted for the light of a frequency

ν

(higher than the threshold frequency

ν

₀) is proportional to

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$ν$ - $ν$ ₀
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threshold frequency ( $ν$ ₀)
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intensity of light
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frequency of light ( $ν$ )

The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the:

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ultraviolet region.
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visible region.
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infrared region.
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X-ray region.

In the phenomenon of electric discharge through gases at low pressure, the colored glow in the tube appears as a result of

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excitation of electrons in the atoms
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collision between the atoms of the gas
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collisions between the charged particles emitted from the cathode and the atoms of the gas
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collision between different electrons of the atoms of the gas

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:

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4
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8
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16
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2

Monochromatic light of frequency 6.0×10¹⁴ Hz is produced by a laser. The power emitted is 2×10^-3 W. The number of photons emitted, on the average, by the source per second is :

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$5 \times 10^{15}$
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$5 \times 10^{16}$
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$5 \times 10^{17}$
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$5 \times 10^{14}$

A photo-cell employs photoelectric effect to convert:

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change in the frequency of light into a change in electric voltage.
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change in the intensity of illumination into a change in photoelectric current.
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change in the intensity of illumination into a change in the work function of the photocathode.
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change in the frequency of light into a change in the electric current.

When photons of energy h $ν$ fall on an aluminium plate (of work function E₀), 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 :

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$K + E_{0}$
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2K
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K
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K+h $ν$

The momentum of a photon of energy 1 MeV in kg m/s, will be :

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$5 \times 10^{- 22}$
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$0.33 \times 10^{6}$
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$7 \times 10^{- 24}$
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$10^{- 22}$

An electron is accelerated through a potential difference of 10,000 V. Its de-Broglie wavelength is, (nearly) : ( $m_{e} = 9 \times 10^{- 31} k g$ )

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12.2 nm
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$12.2 \times 10^{- 13} m$
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$12.2 \times 10^{- 12} m$
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$12.2 \times 10^{- 14} m$

A plane electromagnetic wave of wave intensity 6 W/ $m^{2}$ strikes a small mirror of area 30 $c m^{2}$ , held perpendicular to the approaching wave. The momentum transferred in kg $m s^{- 1}$ by the wave to the mirror each second will be

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(1) $1.2 \times 10^{- 10}$
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(2) $2.4 \times 10^{- 9}$
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(3) $3.6 \times 10^{- 8}$
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(4) $4.8 \times 10^{- 7}$

The work function of a metal surface is 2 eV. When the light of frequency f is incident on the surface, the maximum kinetic energy of photoelectron emitted is 5 eV. If the frequency of the incident light is increased to 4f, then the maximum kinetic energy of the photoelectron emitted will be:

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20 eV
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22 eV
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26 eV
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28 eV

The variation of kinetic energy (K) of photoelectron as a function of frequency f of the incident radiation is best shown by-

Light of frequency 1.5 times the threshold frequency is incident on a photosensitive material. What will be the photoelectric current if the frequency is halved and intensity is doubled?

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four times
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one-fourth
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zero
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doubled

An electron is accelerated from rest through a potential difference of V volt. If the de Broglie wavelength of electron is $1.227 \times 10^{- 2}$ nm, the potential difference is:

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$10^{2} V$
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$10^{3} V$
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$10^{4} V$
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$10^{5} V$

Light of wavelength 488 nm is produced by an argon laser which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the stopping (cut-off) potential of photoelectrons is 0.38 V. Find the work function of the material from which the emitter is made.

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2.16 eV
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3.06 eV
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2.0 eV
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0.38 eV

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Practice Physics Quiz Questions and Answers

0:0:1

Practice Physics Quiz Questions and Answers

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