Question

Calculate the number of photons emitted in 10 hours by a 60 W sodium lamp emitting radiations of wavelength $6000A^o$

Answer 1

$E=nhc/\lambda$

$\lambda =6000\times {10}^{-10}$

$h=6.6\times {10}^{-34}$

$E\left(joule\right)=watt\times second$

$=60\times 10\times 60\times 60=2160000$ J

$n=E\lambda /hc$

after solving we get

$n=6.4\times {10}^{24}$ photons