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MrMoose
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Homework Statement
Radiation of intensity I is normally incident on an object that absorbs a fraction frac of it and reflects the rest back along the original path. What is the radiation pressure on the object?
Homework Equations
Radiation pressure Pr (force/unit area)
Pra = I/c (total absorption)
Prr = 2I/c (total reflection back along path)
The Attempt at a Solution
The object absorbs a fraction frac of the intensity, which I translate mathematically as:
Pra = (frac)*I / c
This would mean that the total intensity reflected is:
Prr = 2*(1 - frac)*I/c
Unfortunately the answer is: Pra = (2 - frac)*I / c
I don't know how they came to this conclusion. Thanks in advance, MrMoose