Q. The momentum of a photon of energy 1 MeV in kg m/s, will be :
A) 0.33 × 10⁶
B) 8 × 10⁻²⁴
C) 5 × 10⁻²³
D) 5 × 10⁻²²
Explanation
[Solution from source] E = 1 MeV = 1.6 × 10⁻¹³ J and p = E/c = 1.6 × 10⁻¹³/(3 × 10⁸) ≈ 5.3 × 10⁻²² kg m/s. Skipping the MeV-to-joule conversion gives a meaningless number, and 5 × 10⁻²³ is off by a factor of ten. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.