Question

A 40-W lightbulb is 1.9 m from a screen. What is the intensity of light incident on the screen? Assume that a lightbulb emits radiation uniformly in all directions (i.e., over 4π steradians). Express your answer with the appropriate units.

Answer 1

Answer:

$INTNESITY = 0.88W/m^{2}$

Explanation:

given data:

power P =  40W

Distance of light bulb from screen is  R  = 1.9 m

The light intensity considered as  the light energy falling on the surface per unit area per unit time

Intensity of light can be determined by using following formula

$intesnity = \frac{P} {4\pi R^{2}}$

$intesnity = \frac{40} {4\pi *1.9^{2}}$

$INTNESITY = 0.88W/m^{2}$