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.
Last updated
Read the Dawn of Modern Physics notesFree MDCAT chapter notes with key terms739 questions · page 35 of 37
- A. Compton Effect
- B. Photoelectric Effect
- C. Nuclear Effect
- D. Pair Production
Explanation: Explanation:For intermediate energy of radiations, the dormant process is Compton effect. This option is not correct.
Correct answer: Compton Effect- A. High frequency
- B. Low frequency
- C. Threshold frequency
- D. Resonance frequency
Explanation: The correct answer is Threshold frequency. This is the minimum frequency of light necessary to eject electrons from a metal surface as…
Correct answer: Threshold frequency- A. α-particle
- B. β-particle
- C. X-rays
- D. γ-radiations
Explanation: In pair production, a high-energy photon interacts with a nucleus to transform into a particle and its antiparticle, such as an electron…
Correct answer: γ-radiations- A. 2.00 x 10^16Hz
- B. 2.00 x 10^14 Hz
- C. 5.00 x 10^16Hz
- D. 2.00 x 10^18 Hz
Explanation: Where h is planck's constant whose value is 6.6x10^-34J.s = 6.6x10^-34/4.42x10^-26 =1.5x10^-8m Now finding frequency of photon: 𝞴xf=c c…
Correct answer: 2.00 x 10^16Hz- A. X-ray
- B. Proton.
- C. Electron.
- D. Photon.
Explanation: Heating the metal filament in the cathode ray tube causes an increase in energy of the filament which enables electrons to be released…
Correct answer: Electron.- A. AM radio
- B. Long radio
- C. Shorter
- D. Both A and C
Explanation: When the temperature of an object is increased it emits light of shorter wavelength according to E=hc/lambda, since the energy of the…
Correct answer: Shorter- A. Mass variation
- B. Energy - mass relationship
- C. Inertia forces
- D. All of these
Explanation: In this case, we look at mass alteration as the speed of object increases.The mathematical expression can be given as, m=mo/√(1-v2/ c2)If…
Correct answer: All of these- A. 4.28 x 10^-7 Wm-2K-4
- B. 4.28 x 10^-4 Wm-2K-4
- C. 3.62 x 10^-4 Wm-2K-4
- D. 5.67 x 10^-8 Wm-2K-4
Explanation: Explanation: The value of Stefan's Boltzmann constant is 5.67 × 10-8Wm-2K-4.
Correct answer: 5.67 x 10^-8 Wm-2K-4- A. 1.68 x 10^-27 m
- B. 1.65 x 10^-29 m
- C. 1.70 x 10^-25 m
- D. 1.66 x 10^-29 m
Explanation: Explanation: The de Broglie's wavelength (λ) of a particle is given by the equation: λ = h / pWhere h is the planck's constant and p is…
Correct answer: 1.66 x 10^-29 m- A. Intense beam of light
- B. Coherent beam of light
- C. Intense, Coherent, Monochromatic beam of light
- D. Monochromatic beam of light
Explanation: Explanation:LASER (Light Amplification by Stimulated Emission of Radiation) is a device that produces a beam of light through the process…
Correct answer: Intense, Coherent, Monochromatic beam of light- A. 2.5 kWm-2
- B. 0.6 kWm-2
- C. 1.4 kWm-2
- D. 2.0 kWm-2
Explanation: Explanation:Solar energy at normal incidence outside the Earth's atmosphere is also known as solar constant.
Correct answer: 1.4 kWm-2- A. 2.90 x 10^-3 mK
- B. 3.34 x 10^-4 mK
- C. 4.22 x 10^-7 mK
- D. 3.42 x 10^-8 mK
Explanation: Wien's Law states that the product of the wavelength corresponding to the maximum intensity of radiation and the temperature of the body…
Correct answer: 2.90 x 10^-3 mK- A. 1.05 x 10^-41 J
- B. 1.05 x 10^-26 J
- C. 1.15 x 10^10 J
- D. 2.19 x 10^-40 J
Explanation: The uncertainty in energy can be determined using the energy-time uncertainty principle: ΔE = h/Δt, where h is Planck's constant…
Correct answer: 1.05 x 10^-26 J- A. 9.108 × 10−30g
- B. 9.108 × 10−25 g
- C. 9.108 × 10−31 g
- D. Too less to be measured
Explanation: 9.108 × 10-30 g: This option represents the approximate weight of an electron.
Correct answer: 9.108 × 10−31 g- A. Hydrogen
- B. Helium
- C. Neon
- D. Carbon dioxide
Explanation: A gas laser is a laser in which an electric current is discharged through a gas inside the laser medium to produce laser light.
Correct answer: Helium- A. Pair production
- B. Compton effect
- C. Annihilation of matter
- D. photoelectric effect
Explanation: A.The creation of an elementary particle and its antiparticle, usually when a photon (or another neutral boson) interacts with a nucleus…
Correct answer: Annihilation of matter- A. Intensity of the incident light
- B. Frequency of the incident light
- C. Temperature of the photosensitive surface
- D. None of the above
Explanation: The maximum KE of emitted photoelectrons depends on the frequency of incident lightThis can be represented by the photoelectric equationEk…
Correct answer: Frequency of the incident light- A. Intensity of light
- B. Frequency of light
- C. Wavelength of light
- D. Speed of light
Explanation: According to Planck's quantum theory, the intensity of the incident beam is directly related to the number of photons in the beam.
Correct answer: Intensity of light- A. E = 0.52 Mev
- B. E < 1.02 Mev
- C. E < 0.52 Mev
- D. E > 1.02 Mev
Explanation: Pair production is a process in which a photon interacts with a nucleus or an atomic electron and produces an electron-positron pair.
Correct answer: E > 1.02 Mev- A. Doubled
- B. More than double
- C. Unchanged
- D. Less than double
Explanation: More than double: From Einstein's equation for photoelectric effect , the maximum kinetic energy , K=hν−W where ν= frequency of incident…
Correct answer: More than double