Q. A beam of circularly polarised light us completely absorbed by an object on which it falls. If $U\ $represents absorbed energy and $\omega$ represents angular frequency, then angular momentum transferred to the object is given by
A) $\frac{U}{\omega^{2}}$
B) $\frac{U}{2\omega}$
C) $\frac{U}{\omega}$
D) $\frac{2U}{\omega}$
Explanation
(c) Angular momentum
$L = \frac{nh}{2\pi}$
$U = nhv$
$\omega = 2\pi v \Rightarrow v = \frac{\omega}{2\pi}$
$\therefore\ \ \ U = \frac{nh\omega}{2\pi}$
Or $U = L\omega$
$\ \ L = \frac{U}{\omega}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.