APSC Legal Metrology: Paper 2 Compton effect

In Compton effect
(A) there is elastic scattering of photon and electron
(B) there is inelastic scattering of photon and electron
(C) wavelength of scattered photon decreases
(D) incident photon energy is completely converted to kinetic energy of the electron

Correct Answer:
(B) there is inelastic scattering of photon and electron

Explanation:
The Compton effect refers to the inelastic scattering of a high-energy photon (like an X-ray or gamma-ray) by a loosely bound or free electron. In the process:

• The photon loses part of its energy to the electron.
• The scattered photon has lower energy (thus longer wavelength) than the incident photon.
• The electron gains kinetic energy and recoils.

So:

• (A) is incorrect because the scattering is inelastic, not elastic.
• (B) is correct.
• (C) is incorrect because the wavelength increases, not decreases.
• (D) is incorrect because only part of the photon’s energy is transferred to the electron.