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Electromagnetic Waves Physics Ncert Solutions Class 12th Physics Class 12th Physics NCERT Exemplar Solutions Class 12th Chapter Eight

An EM wave of intensity I falls on a surface kept in vacuum and exerts radiation pressure p on it. Which of the following are true?

(a) Radiation pressure is I/c if the wave is totally absorbed

(b) Radiation pressure is —I/c if the wave is totally reflected

(c) Radiation pressure is 2I/c if the wave is totally reflected

(d) Radiation pressure is in the range I/c < p < 2I/c for real surfaces

2 Views | Posted 4 months ago

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Answered by

Payal Gupta | Contributor-Level 10

4 months ago

This is a multiple choice answer as classied in NCERT Exemplar

momentum per unit time per unit area = intensity/ speed of wave

= I/c= radiation pressure (p)

Momentum is always double when a light gets reflected back as in that case the momentum which is positive to one side added to momentum which is negative to other side so momentum is always double

So it becomes 2I/c

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