Question

A photon of wavelength 6630 k is incident on a totally reflecting surface. The momentum delivered by the photon is equal to

• A. $6.63\times {10}^{-27}k{g}^{-}m/s$
• B. $2\times {10}^{-27}k{g}^{-}m/s$
• C. ${10}^{-27}k{g}^{-}m/s$
• D. None of the above

Answer 1

Answer: (B)

$P=n\left(\frac{E}{t}\right)$ $10kWh=n\left[\frac{200MeV}{t}\right]$ $10\times {10}^3\times 60\times 60=n\times 200\times {10}^6\times 1.6\times {10}^{-19}$ $(\because t=1)$ $n=\frac{10\times {10}^3\times 60\times 60}{200\times {10}^6\times 1.6\times {10}^{-19}}$ $n=\frac{36\times {10}^{19}}{200\times 1.6}$ $n=\frac{360\times {10}^{18}}{200\times 1.6}$ $n=1.125\times {10}^{18}$ $n=11.25\times {10}^{17}$