Chapter 27, Problem 43A

The intensity of light decreases as the inverse square of the distance from the source. Does this mean that light energy is lost? Explain.

To determine

To explain that whether the light energy gets lost since the intensity of light decreases as the inverse square of the distance from the source.

Answer to Problem 43A

This is known as inverse square law of light which states that the intensity of light decreases as the inverse square of the distance from the source. It does not mean the light energy gets lost in fact it says the light intensity becomes weaker when moving away from the source keeping the total energy remains constant in all direction over a spherical sphere for all value of distances measured from source.

Explanation of Solution

Introduction:

Inverse square law of light states that the intensity of light decreases as the inverse square of the distance from the source.

Light energy does not get lost in fact it spreads out equally in all directions. In other words; the light intensity becomes weaker when moving away from the source keeping the total energy remains constant in all direction over a spherical sphere for all value of distances measured from source.

Conclusion:

Thus, light energy does not get lost in fact the light intensity becomes weaker when moving away from the source.