Question

Estimate the radiation pressure due to a bulb that emits 25 W of EM radiation at a distance of 7.5 cm from the center of the bulb. Assume that light is completely absorbed.

Answer 1

Given Information:

Wattage of bulb = W = 25 W

distance = d = 7.5 cm = 0.075 m

Required Information:

Radiation Pressure = ?

Answer:

Radiation Pressure = 1.179x10⁻⁶ N/m²

Step-by-step explanation:

The radiation pressure is given by

P = I/c

Where c = 299792458 m/s is the speed of light and I is the intensity of radiation and given by

I = W/4πd²

Where W is the wattage of bulb and d is the distance

I = 25/4π*0.075²

I = 353.67 w/m²

so the radiation pressure becomes

P = 353.67/299792458

P = 1.179x10⁻⁶ N/m²

Therefore, the radiation pressure due to a 25 W bulb at a distance of 7.5 cm is 1.179x10⁻⁶ N/m²