Free Photons and the Particle Model of Light MCQs with Answers

• A. λo/4
• B. λo/2
• C. 2 λo
• D. 4 λo

Explanation: The explanation is given below: Work function = Wo = hc/λoIf work function is Wo/2 = hc/λ1Then λ1 = 2λ0

• A. 0.51 MeV
• B. 1.02 MeV
• C. 0.32 MeV
• D. 0.85 MeV

Explanation: In pair production, a proton with energy, greater than or equal to 1.02 MeV is required to create a pair of electron and positron.

• A. Visible light photon
• B. X-ray photon
• C. Y-ray photon
• D. U.V. photon

Explanation: When a Y-ray photon passes close to an atomic nucleus and it possesses energy greater than 1.02 MeV, the photon is converted into…

• A. Ee= 1.02 MeV, Ep=1.02 MeV
• B. Ee= 0.51 MeV, Ep=1.02 MeV
• C. Ee= 1.02 MeV, Ep=0.51 MeV
• D. Ee= 0.51 MeV, Ep=0.51 MeV

Explanation: The explanation is given below: The rest mass energy for both electron and positron is 0.51 MeV.

• A. 4.1 MeV
• B. 2.05 MeV
• C. 1.02 MeV
• D. 0.51 MeV

Explanation: We know, that in pair production momentum and energy are conserved. By conserving energy, E total = Ee + Ep 4.1 MeV = Ee + Ep Now, by…

• A. Maxwell
• B. Hertz
• C. Einstein
• D. Heisenberg

Explanation: The photoelectric effect was discovered in 1887 by the German physicist Heinrich Rudolf Hertz.

• A. Pressure
• B. Temperature
• C. Intensity
• D. Frequency

Explanation: The frequency of the light determines the maximum kinetic energy of the emitted electrons.

• A. Maxwell
• B. Hertz
• C. Einstein
• D. Bohr

Explanation: The scientist who first explained how a photon can transfer its energy into an electron was Albert Einstein.

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

Explanation: In the Compton effect, the photon collides with an electron at rest and transfers some of its energy to the electron.

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

Explanation: The correct answer is diffraction. Diffraction is a phenomenon in which light bends around obstacles or through slits, which is a…

• A. Neutron
• B. Proton
• C. Photon
• D. Positron

Explanation: The positron is a particle with the same mass as an electron but with the opposite charge.

• A. Zero
• B. Less than speed of positron
• C. Equals to speed of positron
• D. Greater than speed of positron

Explanation: In electron-positron pair production, a photon with energy greater than or equal to 1.02 MeV (the rest mass energy of an electron and a…

• A. K.E of all the emitted electrons
• B. Mean K.E of emitted electrons
• C. Maximum K.E of emitted electron
• D. Minimum K.E of emitted electrons

Explanation: The photoelectric equation K = hf - Φ is used to calculate the maximum kinetic energy of the emitted electron during the photoelectric…

• A. 1.02 keV
• B. 1.02 MeV
• C. 1.02 eV
• D. 1.02 GeV

Explanation: Pair production occurs when the energy of the photon is at least 1.02 MeV.

• A. Mass is not conserved
• B. Energy is not conserved
• C. Momentum is not conserved
• D. Charge is not conserved

Explanation: Correct answer: C) Momentum is not conserved. The principle of conservation of momentum states that the total momentum of an isolated…

• A. Electron
• B. β-particle
• C. Proton
• D. All

Explanation: To summarize, a positron (β+) has a charge in magnitude equal to the charge on an electron (e-), a β-particle (which can be an electron or…

• A. Momentum
• B. Frequency
• C. Mass
• D. All of these

Explanation: In quantum physics, wave-particle duality states that any particle or quantum phenomenon can be represented as either a particle or a…

• A. Momentum of photon is given by h/λ
• B. Rest mass of photon is zero
• C. Photon exert no pressure
• D. Energy of photon is hν

Explanation: The correct answer is that photons exert no pressure, which is incorrect.

• A. Mass
• B. Energy
• C. Intensity
• D. None of these

Explanation: The intensity of light is directly related to the number of photons. When two photons move in the same direction, the intensity will…

• A. Appears as photon
• B. Appears as an electron- positron pair
• C. Appears as its K.E.
• D. It vanishes

Explanation: When a fast-moving electron loses energy, it can emit a photon. This phenomenon is known as bremsstrahlung radiation or braking…