Question

Light of intensity 12 W/m\(^2\) is incident on 4 cm\(^2\) black surface. Find radiation pressure.

• A. \( 1 \times 10^{-8}\ \text{Pa} \)
• B. \( 4 \times 10^{-8}\ \text{Pa} \)
• C. \( 1.6 \times 10^{-7}\ \text{Pa} \)
• D. \( 4.8 \times 10^{-7}\ \text{Pa} \)

Hint:

Radiation pressure on a perfectly absorbing surface: \( P = \frac{I}{c} \)

Answer 1

The Correct Option is B

Radiation pressure on black body: \[ P = \frac{I}{c},\quad I = 12\ \text{W/m}^2,\quad c = 3 \times 10^8 \Rightarrow P = \frac{12}{3 \times 10^8} = 4 \times 10^{-8}\ \text{Pa} \]