- #1

duran9987

- 12

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## Homework Statement

Compute the radiation pressure exerted by a gas of photons (according to kinetic theory). There are N photons, each with energy hf, the momentum is hf/c, and the walls are perfectly reflecting. Express the pressure in terms of N, V, and the product hf.

## Homework Equations

Pressure = (1/3)*(Nk/V) (mv^2) , where v^2 is an average

Pressure = Force / Area

Speed of Photons = λf

Force on Area A = (Number of collisions on the wall in time Δt)(Momentum transferred to the wall per collision)/(Δt)

## The Attempt at a Solution

The momentum transferred to the wall by the photons is 2(hf/c)

The number of collisions = ((λf)ΔtA)(1/2)(N/V)

Force on Area A = (hf/c)(A)(N/V)(λf)

Multiply both Sides by Area to get pressure = P = (1/3)h(f^2)λ(N/V)(1/c)

Not sure how to express it in terms of the product hf.