Question

A light source radiates 60.0 W of single-wavelength sinusoidal light uniformly in all directions. What is the average intensity of the light from this bulb at a distance of 0.400 m from the bulb

Answer 1

Answer: $29.85\ W/m^2$

Explanation:

Given

Power $P=60\ W$

Distance from the light source $r=0.4\ m$

Intensity is given by

$I=\dfrac{P}{4\pi r^2}$

Inserting values

$\Rightarrow I=\dfrac{60}{4\pi (0.4)^2}\\\\\Rightarrow I=\dfrac{60}{2.010}\\\\\Rightarrow I=29.85\ W/m^2$

Answer 2

Answer:

29.85 W/ m^2

Explanation: