Free Dawn of Modern Physics MCQs with Answers
739 Dawn of Modern Physics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Classical physics cannot explain blackbody radiation and related observations, leading to Planck’s quantum theory, in which energy is emitted or absorbed in discrete packets. Photons provide the particle model of light, with energy and momentum linked to frequency and wavelength, including the photoelectric effect and its threshold frequency.
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Read the Dawn of Modern Physics notesFree MDCAT chapter notes with key terms739 questions · page 36 of 37
- A. Max Planck
- B. Compton
- C. Lousie
- D. Einstein
Explanation: Albert Einstein was awarded the Noble Prize in Physics in 1921 for his explanation of the photoelectric effect, which he published in…
Correct answer: Einstein702. The scattering angle for which the Compton shift in wavelength is equal to Compton wavelength is:
- A. 0=90°
- B. 0=0"
- C. 0=45°
- D. 0=180°
Explanation: COMPTON'S EFFECT: It is the scattering of a high-frequency photon after a collision with an electron, which results in a decrease in the…
Correct answer: 0=90°- A. The photon's frequency only
- B. The metal work function and photon's frequency
- C. The intensity of incident light
- D. None of the above
Explanation: The maximum kinetic energy of an electron ejected from a metal by a photon is calculated using the equation K_max = hf - φ, where h is…
Correct answer: The metal work function and photon's frequency- A. Critical frequency
- B. Threshold frequency
- C. Work function
- D. None of the above
Explanation: This minimum frequency is also called the threshold frequency, and the value of ν0 \nu, start subscript, 0, end subscript depends on the…
Correct answer: Threshold frequency- A. v = f.λ
- B. λ = h / mv
- C. s = d/t
- D. p = λ x h
Explanation: The correct formula to calculate the wavelength of an electron is λ = h / mv, known as De Broglie's wave equation.
Correct answer: λ = h / mv- A. Blue light
- B. Yellow light
- C. X-rays
- D. Radio wave
Explanation: According to the de Broglie equation, wavelength and momentum are inversely proportional.
Correct answer: X-rays- A. 00
- B. 450
- C. 900
- D. 1800
Explanation: The largest change in wavelength occurs when the photon is scattered through 180 degrees because the photon is reflected directly back in…
Correct answer: 1800- A. Increase in intensity of light
- B. Increase in wavelength of light
- C. Increase in frequency of light
- D. Never
Explanation: The correct answer is that the number of ejected photoelectrons increases with an increase in the intensity of light.
Correct answer: Increase in intensity of light- A. Stopping potential
- B. Maximum kinetic energy of Photoelectron
- C. Photoelectric current
- D. Both (A) & (B)
Explanation: If the frequency of the incident radiation in the photoelectric effect is increased beyond the threshold frequency, it will affect the…
Correct answer: Stopping potential- A. The number of photons
- B. The energy of each photon
- C. The speed of the photons
- D. The frequency of photons
Explanation: Einstein proposed the idea that light is quantized into discrete packets of energy called photons.
Correct answer: The number of photons- A. Compton effect
- B. Photoelectric effect
- C. Pair production
- D. Pair Annihilation
Explanation: Pair production is the process in which a photon interacts with a nucleus and produces an electron-positron pair.
Correct answer: Photoelectric effect- A. Space
- B. Inertial frame of reference
- C. Speed of light
- D. Time
Explanation: In Physics, a dimension can be defined as the magnitude of something in a particular direction.
Correct answer: Time- 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 MeV720. 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