Free Quantum Theory and Radiation MCQs with Answers
147 Quantum Theory and Radiation MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Quantum theory treats electromagnetic radiation as packets of energy called photons, with energy proportional to frequency through E equals hf. The topic covers Planck's hypothesis, photon momentum, the photoelectric effect, threshold frequency, work function and wave particle duality, distinguishing quantised energy exchange from classical continuous radiation.
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147 questions · page 7 of 8
- A. 0.511 MeV
- B. 1 MeV
- C. 8.0x10 J
- D. None of the above
Explanation: Eo=moc^2Where,c2= velocity of light which is 3×10^8 m/smo=rest mass of an electron which is 9.11×10−31 kgEo=rest mass energyPut value of…
Correct answer: 0.511 MeV- A. Slower
- B. Faster
- C. Same
- D. Clicks negative time
Explanation: According to Einstein's Special Theory of Relativity, Time for a moving reference frame actually slows down compared to a "stationary"…
Correct answer: Slower- A. will shift towards the longer wavelength
- B. will shift towards the shorter wavelength
- C. will not change
- D. None of these
Explanation: As the temperature of the blackbody increases, the peak wavelength decreases (Wien's Law).
Correct answer: will shift towards the shorter wavelength- A. Remain constant
- B. Become zero
- C. Become equal to rest mass of particle
- D. Become infinite
Explanation: Using the formula for mass dilationWhen an object travels at v = c, the factor becomes equal to zero.Dividing mo by zero leads to mass…
Correct answer: Become infinite- A. Spontaneous emission
- B. Ordinary emission
- C. Absorption of radiation
- D. Stimulated emission
Explanation: Laser stands for Light Amplification by Stimulated Emission of Radiation. Laser light utilizes stimulated emission.
Correct answer: Stimulated emission- A. ΔpΔx = h
- B. ΔEΔI=h
- C. Both (a) and (b)
- D. None
Explanation: The Heisenberg uncertainty principle explains that momentum and position of a particle cannot be simultaneously at the same time with 100%…
Correct answer: Both (a) and (b)- A. 0.511 MeV
- B. 1 MeV
- C. 8.0 x 10^-14 J
- D. None of the above
Explanation: The rest mass energy of a particle is calculated by the formula E = mc2, where m is the rest mass and c is the speed of light.
Correct answer: 0.511 MeV128. To an observer stationary on a plateform a compared to a stationary clock and a moving clock clicks:
- A. slower
- B. faster
- C. same rate as stationary clock
- D. clicks negative time
Explanation: The correct answer is that the moving clock ticks slower as observed from a stationary platform.
Correct answer: slower- A. Infinite
- B. Zero m
- C. 2 meter
- D. None of above.
Explanation: Formula for length contraction is L=L0√1−v2/c2, where: • L = new length (m) • L0 = original length (m) • v = speed of object (ms−1) • c =…
Correct answer: Zero m- A. 0.51 joule
- B. 1.02 joule
- C. 9.11 x 10^-32 joule
- D. 8.2 x 10^-14 joule
Explanation: The rest mass energy of an electron can be calculated using Einstein's equation:E = mc²E = 9.11 × 10-31 × (3 × 108)²E = 9.11 × 10-31 × 9 ×…
Correct answer: 8.2 x 10^-14 joule- A. Equal to the speed of light
- B. Greater than speed of light
- C. Comparable to the speed of light
- D. None of these
Explanation: When a charge moves at a relativistic speed, it means it is moving at a significant fraction of the speed of light, approaching but not…
Correct answer: Comparable to the speed of light- A. ionized state
- B. stimulations
- C. population inversion
- D. all of these
Explanation: GROUND STATE: The ground state of an electron, the energy level it normally occupies, is the state of lowest energy for that electron.
Correct answer: population inversion- A. photoelectric effect
- B. compton effect
- C. penetrating effect
- D. diffraction
Explanation: The wave nature of an electron is illustrated by its electron diffraction, as explained by davisson germer experiment.
Correct answer: diffraction- A. double
- B. four times
- C. six times
- D. sixteen times
Explanation: BLACK BODY: A blackbody is a theoretical or model body that absorbs all radiation falling on it, reflecting or transmitting none.
Correct answer: sixteen times- A. penetrating power of x-ray increases
- B. intensity of x-rays increases
- C. wavelength of x-rays increases
- D. all of these
Explanation: X-RAY TUBE: An X-ray tube is a vacuum tube that converts electrical input power into X-rays.
Correct answer: intensity of x-rays increases- A. Photon
- B. Roton
- C. Positron
- D. Antineutrino
Explanation: Antimatter is a type of matter made up of antiparticles. A positron is the antiparticle of an electron, making it the correct answer.
Correct answer: Positron- A. Wave-particle duality
- B. Only wave nature
- C. Only particle nature
- D. Neither wave nor particle nature
Explanation: According to debroglie , all mater particles in motion have dual nature and thus he derived an equation which is E=hc/λ
Correct answer: Wave-particle duality- A. 7.3 × 10 -34 m
- B. 1.1 × 10 -34 m
- C. 1.8 × 10 -35 m
- D. 9.9 × 10 -34 m
Explanation: λ= h/mv = 6.626 x 10-34 / 0.02 x 300 = 1.1 × 10 -34 m
Correct answer: 1.1 × 10 -34 m- A. The photoelectric effect
- B. The Compton effect
- C. The spectral radiation form cavity radiation
- D. The reflection of electrons by crystal
Explanation: By Huygens principle, reflection of electrons shows the wave nature of light. So, D is the answer.
Correct answer: The reflection of electrons by crystal- A. Line spectra of action
- B. The production of x-rays
- C. The photoelectric erect
- D. Electrons diffraction by crystalline material
Explanation: The wave properties of electrons can be demonstrated through diffraction, superposition and interference.
Correct answer: Electrons diffraction by crystalline material