JEE PYQ: Motion In Two Dimensions Question 9
Question 9 - 2020 (04 Sep Shift 1)
A beam of plane polarised light of large cross-sectional area and uniform intensity of 3.3 Wm$^{-2}$ falls normally on a polariser (cross sectional area $3 \times 10^{-4}$ m$^2$) which rotates about its axis with an angular speed of 31.4 rad/s. The energy of light passing through the polariser per revolution, is close to:
(a) $1.0 \times 10^{-5}$ J (b) $1.0 \times 10^{-4}$ J (c) $1.5 \times 10^{-4}$ J (d) $5.0 \times 10^{-4}$ J
Show Answer
Answer: (d)
Solution
Average energy $= I_0 A \langle\cos^2\theta\rangle = \frac{(3.3)(3 \times 10^{-4})}{2} = 5 \times 10^{-4}$ J per revolution.
BETA
