Quantum Quiz March 21

41 Questions | By Saptghosh80 | Last updated: Mar 21, 2022 | Total Attempts: 597

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1.

The Compton shift Δλ is twice the Compton wavelength if the scattering angle is
- A.
  
  90°
- B.
  
  180°
- C.
  
  45°
- D.
  
  0°
2.

The Davisson-Germer experiment demonstrates
- A.
  
  Electroluminescence
- B.
  
  Thermionic emission
- C.
  
  Electron diffraction
- D.
  
  X-ray diffraction
3.

According to Rayleigh-Jeans' radiation law, the emissive power of a blackbody over a wavelength range λ to λ+dλ is proportional to λⁿ. Then n is
- A.
  
  4
- B.
  
  1
- C.
  
  -2
- D.
  
  -4
4.

The rest mass of a photon of frequency ν is
- A.
  
  Hν/c
- B.
  
  Hν/c²
- C.
  
  Zero
- D.
  
  Hν²/c
5.

What is the speed of a particle whose mass is 3 times its rest mass?
- A.
  
  2c/3
- B.
  
  C/3
- C.
  
  √2c
- D.
  
  2√2c/3
6.

In Compton scattering, if the angle of scattering varies from 0º to 180º, the electron's recoil angle varies from
- A.
  
  0º to 90º
- B.
  
  90º to 180º
- C.
  
  0º to 180º
- D.
  
  0º to 45º
7.

The radiated intensity per unit time from a cavity kept at temperature 1000 Kelvin is 5.67x10ⁿ W/m². The value of n is
- A.
  
  8
- B.
  
  6
- C.
  
  4
- D.
  
  12
8.

The de Broglie wavelength of an electron accelerated by a potential of 150 V is
- A.
  
  0.08 Å
- B.
  
  1 Å
- C.
  
  12.26 Å
- D.
  
  150 Å
9.

The momentum of an electron (rest mass energy = 0.5 MeV) is 1 MeV/c. Its energy in MeV is
- A.
  
  1.5
- B.
  
  1.12
- C.
  
  1.22
- D.
  
  2.22
10.

The de Broglie wavelength of a thermal neutron of mass m at temperature T is given by λ =
- A.
  
  H/√(3mkT)
- B.
  
  H/√(2mkT)
- C.
  
  √3h/(mkT)
- D.
  
  3h/√(2mkT)
11.

In Davisson-Germer's experiment the highest peak was obtained at an angle θ = 50° with a voltage of 54 V. The de Broglie wavelength of electrons was
- A.
  
  1.67 Å
- B.
  
  0.167 Å
- C.
  
  0.227 Å
- D.
  
  2.27 Å
12.

A proton accelerated through a potential difference of V has the same de Broglie wavelength as an α-particle subjected to a potential difference of
- A.
  
  4V
- B.
  
  V/4
- C.
  
  V/8
- D.
  
  8V
13.

GaP, a semiconductor with an energy gap of 2.25 eV, is used to make LEDs. The wavelength of emitted light from pure GaP is
- A.
  
  705 nm
- B.
  
  515 nm
- C.
  
  630 nm
- D.
  
  555 nm
14.

The peak wavelengths of radiation of a red-hot and a yellow-hot object are 630 nm and 570 nm respectively. If the red-hot object's temperature is 5000 K, the other's temperature is
- A.
  
  4000 K
- B.
  
  4500 K
- C.
  
  5000 K
- D.
  
  5500 K
15.

In relation to Rayleigh-Jeans law, the ultraviolet catastrophe refers to the prediction
- A.
  
  E(ν) → 0 as ν → 0
- B.
  
  E(T) → ∞ as T → 0
- C.
  
  E(λ) → ∞ as λ → 0
- D.
  
  E(λ) → ∞ as λ → ∞
16.

According to Planck, the average energy of cavity oscillators in the frequency range ν to ν+dν is given by
- A.
  
  Hν/(exp[hν/kT] - 1)
- B.
  
  Hν/(exp[hν/kT] + 1)
- C.
  
  Hν
- D.
  
  Hν.exp[-hν/kT]
17.

The energy of photons contained in visible light of wavelength 600 nm is
- A.
  
  2 eV
- B.
  
  2 keV
- C.
  
  2 MeV
- D.
  
  0.02 eV
18.

If visible light is used in Compton scattering the Compton shift will be
- A.
  
  Negative
- B.
  
  Zero
- C.
  
  More positive than what is observed with X-rays
- D.
  
  Positive but not detectable in the visible window
19.

The number of oscillation modes per unit volume for em standing waves of frequency ν in a blackbody cavity is proportional to
- A.
  
  ν³
- B.
  
  ν²
- C.
  
  ν
- D.
  
  Hν/(exp[hν/kT] - 1)
20.

The Compton shift Δλ is half the Compton wavelength if the scattering angle is
- A.
  
  45°
- B.
  
  90°
- C.
  
  60°
- D.
  
  180°
21.

Compton scattering is performed on blocks of carbon and silver. If I and I' are the intensities of the unmodified (λ) and Compton-shifted (λ') lines in the scattered X-rays, then
- A.
  
  I > I' for both carbon and silver
- B.
  
  I = I' for both carbon and silver
- C.
  
  I > I' for carbon, I < I' for silver
- D.
  
  I < I' for carbon, I > I' for silver
22.

For cavity radiation of wavelength λ at absolute temperature T, Wien's radiation law corresponds to Planck's law when
- A.
  
  Photon's energy
- B.
  
  Photon's energy >> kT
- C.
  
  Photon's energy = kT
- D.
  
  Photon's energy has any finite value
23.

If one measures the energy of a photon accurately the uncertainty in the measurement of frequency becomes
- A.
  
  Zero
- B.
  
  ∞
- C.
  
  1
- D.
  
  ½
24.

If the measured momentum of an electron is 3.20 x10ˉ²⁷ kg-m/s with an uncertainty of 1.6 x10ˉ²⁹ kg-m/s, what is the minimum uncertainty in the determination of its position?
- A.
  
  1.3 nanometer
- B.
  
  1.3 micrometer
- C.
  
  3.3 nanometer
- D.
  
  3.3 micrometer
25.

The Compton wavelength for electron is
- A.
  
  0.24 Å
- B.
  
  0.024 Å
- C.
  
  2.4 Å
- D.
  
  0.0024 Å