Physics - Modern Physics Question with Solution | TestHub

Energy carried by$n$photons per second

$P=n.\frac{hc}{\lambda }$

As photons get absorbed by dark plate, force experienced by the plate

$F=\frac{1}{C}.n\frac{he}{\lambda }$

Or$F\times c=n.\frac{hc}{\lambda }$$\left[\mathrm{a}\mathrm{s}\mathrm{ }\mathrm{p}\mathrm{o}\mathrm{w}\mathrm{e}\mathrm{r}\mathrm{ }\left(\mathrm{P}\right)=\mathrm{f}\mathrm{o}\mathrm{r}\mathrm{c}\mathrm{e}\times \mathrm{s}\mathrm{p}\mathrm{e}\mathrm{e}\mathrm{d}\right]$

$=F\times c$

Or$n=\frac{F\lambda }{h}=\frac{6.62\times {10}^{-5}\times 5\times {10}^{-7}}{6.62\times {10}^{-34}}=5\times {10}^{22}$