Question

Which of the following phenomenon/phenomena contribute to intensity loss of electromagnetic radiation during transmission through a medium?

• A. Electronic absorption
• B. Rayleigh scattering
• C. Photon–phonon interaction
• D. Stimulated emission

Hint:

Absorption and scattering are primary causes of attenuation in media, while stimulated emission increases intensity (basis of lasers).

Answer 1

The Correct Option is A, B, C

Step 1: Electronic absorption.
When photons interact with electrons in the medium, they can be absorbed, raising electrons to higher energy levels. This removes energy from the transmitted beam. \[ \Rightarrow \text{Leads to intensity loss.} \] Thus, (A) is correct.

Step 2: Rayleigh scattering.
Rayleigh scattering occurs due to elastic scattering of light by particles smaller than the wavelength. This causes light to deviate from its forward path. Even though energy is conserved, transmitted beam intensity decreases because some light is scattered out. \[ \Rightarrow \text{Intensity decreases.} \] Thus, (B) is correct.

Step 3: Photon–phonon interaction.
Photons can interact with lattice vibrations (phonons), leading to inelastic scattering (Raman scattering) or absorption of photons’ energy into vibrational modes. This reduces the transmitted beam intensity. \[ \Rightarrow \text{Causes loss.} \] Thus, (C) is correct.

Step 4: Stimulated emission.
In stimulated emission, an incoming photon induces emission of a second photon of the same phase and direction. This adds photons to the beam instead of removing them. \[ \Rightarrow \text{Does not cause intensity loss; it increases intensity.} \] Thus, (D) is incorrect. Final Answer:
\[ \boxed{(A), (B), (C)} \]