A $100 \;W$ sodium lamp radiates energy uniformly in all directions. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of the sodium light is $589\; nm$.
$(a)$ What is the energy per photon associated with the sodium light?
$(b)$ At what rate are the photons delivered to the sphere?
A $100 \;W$ sodium lamp radiates energy uniformly in all directions. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of the sodium light is $589\; nm$.
$(a)$ What is the energy per photon associated with the sodium light?
$(b)$ At what rate are the photons delivered to the sphere?
$P =100 \,W$
$\lambda=589 \,nm$
$(a)$ Energy per photon $=h c / \lambda$ $=3.37 \times 10^{-19} \,J$
$(b)$ No. of photons per $= P / E$ $=3 \times 10^{20}$ Photons/ second
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