A wide, uniform beam of intensity falls at normal incidence on a matt black card of…

PHYSICS · Multi-part · Fermi University Physics · Mechanics & Dynamical Systems · Electricity, Magnetism & Electromagnetism · Momentum, energy and conservation laws

Electricity, Magnetism and Electromagnetism, Ch Plane electromagnetic waves: polarisation, energy flux and radiation pressure

Problem

A wide, uniform beam of intensity

1.50\,\mathrm{kW\,m^{-2}}

falls at normal incidence on a matt black card of area

0.40\,\mathrm{m^{2}}

, which absorbs all the light that reaches it. The card is at rest and the beam covers it completely. Take

c = 3.00\times10^{8}\,\mathrm{m\,s^{-1}}

. ((a)) Find the radiation pressure on the card. ((b)) Find the total force the beam exerts on the card.

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