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 3 of 8
- A. A party filled valence band and totally empty conduction band
- B. A completely filled valence band a totally empty conduction band and a very wide forbidden band
- C. A completely filled valence band a partially filled conduction band and a narrow forbidden band
- D. A partly filled valence band a totally empty conduction band and a wide forbidden band
Explanation: A semiconductor has a filled valence band and a small forbidden energy gap, so some electrons can reach the conduction band at ordinary…
Correct answer: A completely filled valence band a partially filled conduction band and a narrow forbidden band- A. Decreases
- B. Increases
- C. Remains same
- D. First increases then decreases
Explanation: Heating an intrinsic semiconductor supplies energy across its small band gap, creating more electron-hole pairs and increasing the number…
Correct answer: Increases- A. Semi conductor
- B. Conductor
- C. Metals
- D. Non metals
Explanation: Non-metals that are electrical insulators generally have the largest forbidden energy gaps, while metals have overlapping or zero…
Correct answer: Non metals- A. Electrical insulators alone
- B. Electrical conductors alone
- C. Electrical semi conductors alone
- D. All of the above
Explanation: Band theory explains all three classes: conductors have overlapping or partly filled bands, semiconductors have a small forbidden gap, and…
Correct answer: All of the above- A. Kelvin
- B. Newton
- C. Aristotle
- D. Faraday
Explanation: Aristotle wrote Physics, an ancient work discussing nature, motion and change, and it is commonly regarded in general-knowledge questions…
Correct answer: Aristotle- A. Electromagnetic radiations of high mass number
- B. Electromagnetic radiations of very high frequency
- C. Electromagnetic radiations of high wavelength
- D. Electromagnetic radiations of low energy
Explanation: X-rays are electromagnetic radiations of extremely short wavelengths and high frequency, which is why option B is correct.Option C is…
Correct answer: Electromagnetic radiations of very high frequency- A. Interference
- B. Polarization
- C. Diffraction
- D. None of these
Explanation: In the Davisson-Germer experiment, a beam of electrons is fired at a crystal of nickel.
Correct answer: Diffraction- A. Red
- B. Blue
- C. Black
- D. Orange
Explanation: Black is definitely an ideal absorber but we cannot say it has highest temperature.
Correct answer: Blue- A. 4*10^7 joules
- B. 4*10^{17}eV
- C. 6.6 *10^{-20} eV
- D. 4 *times 10 joules
Explanation: Using the uncertainty principle, we find \(\Delta E \geq 3.315 \times 10^{-30}\) J.
Correct answer: 6.6 *10^{-20} eV- A. 10-11
- B. 10-8
- C. 10-3
- D. 10+3
Explanation: In the context of population inversion in a Ruby laser, the correct answer is that atoms can reside in the excited state for a relatively…
Correct answer: 10-3- A. Light amplification by stimulated emission of radiation
- B. Light annihilation by stimulated emission of radiation
- C. Light amplitude of stimulated emission of radiation
- D. Light amplification by stimulated emission of radio
Explanation: Light amplification by stimulated emission of radiation
Correct answer: Light amplification by stimulated emission of radiation- A. It consists of one ray of light
- B. It consists of one wavelength
- C. It consists of carbon monoxide gas
- D. It consists of photons having 1 eV energy
Explanation: Monochromatic light refers to light that has only one wavelength or frequency.
Correct answer: It consists of one wavelength- A. Visible spectrum
- B. X rays
- C. Radio waves
- D. Infrared waves
Explanation: We know that X-rays are produced due to transition of electron from higher shell yo lower shell , producing continuous and characteristic…
Correct answer: X rays- A. Visible
- B. Ultraviolet
- C. Infrared
- D. X-rays
Explanation: Electromagnetic radiation comes in a range of energies, known as the electromagnetic spectrum.
Correct answer: Infrared- A. Reflection
- B. Refraction
- C. Interference
- D. Diffraction
Explanation: In the Davisson-Germer experiment, electrons were scattered off of a nickel crystal.
Correct answer: Diffraction- A. Less uncertainty
- B. High uncertainty
- C. High accuracy
- D. Equal uncertainty
Explanation: The uncertainty principle states that the uncertainty in the position of a particle and the uncertainty in its momentum must always be…
Correct answer: High uncertainty- A. Newton's theory
- B. Einstein's theory
- C. Hertz theory
- D. Special theory of relativity
Explanation: An inertial frame of reference is one that satisfies the following conditions: It is not accelerating. It is not rotating.
Correct answer: Newton's theory- A. Decreased
- B. Increased
- C. Remain same
- D. Maximum
Explanation: The speed of light received by the observer will remain the same, regardless of the motion of the light source.
Correct answer: Remain same- A. Remain same
- B. Decreased
- C. Increased
- D. Doubled
Explanation: The relativistic length of a moving object will be decreased, as seen by an observer moving relative to the object.
Correct answer: Decreased- A. Equal to speed light
- B. Less than the speed of light
- C. Greater than the speed of light
- D. Not comparable with speed of light
Explanation: If the rest mass of a particle is zero, then its speed is the speed of light.
Correct answer: Equal to speed light