Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Electromagnetic Waves

Question:

A plane electromagnetic wave of wave intensity 6 W/m2 strikes a small mirror of area 40 cm2, held perpendicular to the approaching wave. The momentum transferred by the wave to the mirror each second will be:

Options:

6.4 × 10–7 kg–m/s

4.8 × 10–8 kg–m/s

3.2 × 10–9 kg–m/s

1.6 × 10–10 kg–m/s

Correct Answer:

1.6 × 10–10 kg–m/s

Explanation:

In one second

$P=\frac{2 U}{c}=\frac{2 S_{a v} A}{c}=\frac{2 \times 6 \times 40 \times 10^{-4}}{3 \times 10^8}$

= 1.6 × 10–10 kg–m/s