(a) The spectrum of a star peaks at . Use Wien's law, , to find its surface…

PHYSICS · Subjective · Fermi University Physics · Optics & Photonics · Photodetection, photonic sources and quantum optics · Photodetection, photonic sources and quantum optics

Optics and Photonics, Ch The photon

Problem

(a) The spectrum of a star peaks at

290\ \text{nm}

. Use Wien's law,

\lambda_{\max}T = 2.898\times10^{-3}\ \text{m K}

, to find its surface temperature. (b) A He-Ne laser emits

2.00\ \text{mW}

of light at

633\ \text{nm}

. Find the number of photons it emits per second. (c) Sunlight arrives at the Earth with irradiance

I = 1361\ \text{W m}^{-2}

. Find the radiation pressure it exerts on a perfectly absorbing (black) sail and on a perfectly reflecting (mirror) sail held normal to the beam.

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