Physics Test: Practice Questions On Compton Effect!
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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.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
- 3.The rest mass of a photon of frequency ν is
- A.
Hν/c
- B.
Hν/c²
- C.
Zero
- D.
Hν²/c
- 4.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
- 5.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
- 6.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
- 7.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
- 8.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
- 9.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)
- 10.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
- 11.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
- 12.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
- 13.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
- 14.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 → ∞
- 15.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]
- 16.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
- 17.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
- 18.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)
- 19.The Compton shift Δλ is half the Compton wavelength if the scattering angle is
- A.
45°
- B.
90°
- C.
60°
- D.
180°
- 20.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
- 21.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
- 22.If one measures the energy of a photon accurately the uncertainty in the measurement of frequency becomes
- A.
Zero
- B.
∞
- C.
1
- D.
½
- 23.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
- 24.The Compton wavelength for electron is
- A.
0.24 Å
- B.
0.024 Å
- C.
2.4 Å
- D.
0.0024 Å
- 25.The disagreement between Rayleigh-Jeans' predictions and experimental results for blackbody radiation spectrum is known as
- A.
Infrared signature
- B.
Twin paradox
- C.
Ultraviolet catastrophe
- D.
Gibb's paradox
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