Free Dawn of Modern Physics MCQs with Answers

• A. Electrons
• B. Protons
• C. Neutrons
• D. None of the above

Explanation: The process by which free electrons are emitted from the metal surface when external heat energy is supplied is called thermionic emission.

• A. Different for different materials
• B. Same for all materials
• C. Neither different nor the same
• D. Random

Explanation: The threshold frequency in the photoelectric effect is indeed different for different materials.

• A. Temperature of surface
• B. The intensity of incident light
• C. Frequency of incident light
• D. All of the above

Explanation: In the photoelectric effect, the amount of kinetic energy of emitted photoelectrons depends on the frequency of the incident light.

• A. Photo cell
• B. Battery
• C. Dry cell
• D. Photo diode

Explanation: A device based on the photoelectric effect is commonly referred to as a "photoelectric cell" or "photocell." Photoelectric cells are…

• A. Compton effect
• B. Photoelectric effect
• C. Pair production
• D. None of the above

Explanation: The process of scattering of an X-ray photon by an electron is called "Compton scattering" or "Compton effect." This phenomenon was…

• A. hc/f
• B. fc/h
• C. hf/c
• D. hfc

Explanation: The momentum of photon of frequency f is: P = hf/c This expression shows that the momentum of a photon is directly proportional to its…

• A. Wave nature
• B. Particle nature
• C. Particle-wave nature
• D. None of the above

Explanation: The Compton effect is a phenomenon in which electromagnetic waves, specifically X-rays, exhibit both particle-like and wave-like…

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Explanation is given below in the attached image.

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Explanation is given below in the attached image.

• A. Compton effect
• B. Annihilation of matter
• C. Pair production
• D. All of the above

Explanation: The process of a photon disintegrating into an electron and a positron upon striking a nucleus is known as "pair production." In pair…

• A. Annihilation
• B. Pair production
• C. Compton effect
• D. Photoelectric effect

Explanation: The term "materialization of energy" is often used to describe the process of annihilation of matter, where particles and their…

• A. An electron
• B. A neutron
• C. A psi-meson
• D. None of the above

Explanation: The positron is the antiparticle of the electron. Both the electron and the positron have the same mass but opposite electric charge.

• A. Pair production
• B. Compton effect
• C. Photoelectric effect
• D. Photo cell

Explanation: The given relation holds during the pair production process, where a high-energy photon is converted into an electron-positron pair.

• A. 3 Mev
• B. 4 Mev
• C. 1.02 Mev
• D. Zero

Explanation: The mass m of a single electron is equivalent to 0.511 million electron volts (MeV) of energy E as calculated from the equation formulated…

• A. Pair Annihilation
• B. Compton effect
• C. Photoelectric effect
• D. None of the above

Explanation: The annihilation of matter is the opposite of pair production. In pair production, photon energy is changed into an electron-positron pair…

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Explanation is given below in the attached image.

• A. 9.11 x 10^-31 J
• B. 6.7 Mev
• C. 0.511 Mev
• D. 1.67 x 10^-27 J

Explanation: The electron rest mass (symbol: me) is the mass of a stationary electron, also known as the invariant mass of the electron.

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Explanation is given below in the attached image.

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Explanation is given below in the attached image.

• A. work
• B. work function
• C. power
• D. wavelength

Explanation: The energy required to remove an electron from the surface of a metal is known as the work function.