BITSAT2020PhysicsDual Nature of MatterActual
A plane electromagnetic wave is incident on a plane surface of area A, normally and is perfectly reflected. If energy E strikes the surface in timet then average pressure exerted on the surface is ( c = speed of light )
Options
- Azero
- BE / Atc
- C2 E / Atc
- DE / c
Correct answer
C. 2 E / Atc
Step-by-step solution
Incident momentum, p = E c For perfectly reflecting surface with normal incidence p =2 p = 2 E c F = p t = 2 E ct P = F A = 2 E ctA