Power of the sodium lamp is given as 
Wavelength of the emitted sodium light is given as 
![\[=589 \times 10^{-9} \mathrm{~m}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-50dc3ff82dcae37180f4219c1db5bee2_l3.png "Rendered by QuickLaTeX.com")
Planck’s constant,
Speed of light,
(a)
The energy per photon associated with the sodium light can be calculated as:
![\[\mathrm{E}=\frac{h c}{\lambda}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-5e2aa7d0af2d5bc514d7f111c14b3ae3_l3.png "Rendered by QuickLaTeX.com")
![\[=3.37 \times 10^{-19} \mathrm{~J}=\frac{3.37 \times 10^{-19}}{1.6 \times 10^{-19}}=2.11 \mathrm{eV}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-55d79dbc096e03260f329ac4aaf77bc1_l3.png "Rendered by QuickLaTeX.com")
(b)
is the number of photons delivered to the sphereThe equation for power can be written as:
![\[\mathrm{P}=\mathrm{nE}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-177d19053f7e3a884dda8bea6685ac7e_l3.png "Rendered by QuickLaTeX.com")
So,,
![\[=\frac{100}{3.37 \times 10^{-19}}=2.96 \times 10^{20} \text { photons } / \mathrm{s}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-0edf10032d11c3fc0e75ec14452eaad4_l3.png "Rendered by QuickLaTeX.com")
As a result, the number of photons delivered every second to the sphere is
.