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Q.
A photon of wavelength $6630\,\mathring{A}$is incident on a totally reflecting surface. The momentum delivered by the photon is equal to
Dual Nature of Radiation and Matter
Solution:
The momentum of the incident radiation is given as $p=\frac{h}{\lambda}$.
When the light is totally reflected normal to the surface the direction of the ray is reversed.
That means it reverses the direction of its momentum without changing its magnitude
$\therefore \Delta p=2 p=\frac{2 h}{\lambda}$
$=\frac{2 \times 6.6 \times 10^{-34}}{6630 \times 10^{-10}}$
$ =2 \times 10^{-27} kg - m / \sec$