Question

An object is placed in a medium of refractive index 3. An electromagnetic wave of intensity \(6 \times 10^8\, W/m^2\) falls normally on the object and it is absorbed completely. The radiation pressure on the object would be (speed of light in free space = \(3 \times 10^8\, m/s\)) : 

(1) \(36\, Nm^{-2}\)

(2) \(18\, Nm^{-2}\)

(3) \(6\, Nm^{-2}\)

(4) \(2\, Nm^{-2}\)

Answer 1

 The correct option is (3) \(6\, Nm^{-2}\)

Radiation pressure = \(\frac{I}{v}\)

\(= \frac{I.\mu}{c}\)

\(= \frac{6\times 10^8 \times 3}{3 \times 10^8}\)

\(= 6\, N/m^2\)