Chapter 5, Problem 62TS

Consider a bright point light source located 1 m from a square opening with an area of 1 ${\text{m}}^{\text{2}}$. Light passing through the opening illuminates an area of $4{\text{ m}}^{\text{2}}$ on a wall $2\text{ m}$ from the opening. (a) Find the areas that would be illuminated if the wall were moved to distances of $3\text{ m}$, $5\text{ m}$, and $10\text{ m}$ from the opening. (b) How can the same amount of light illuminate more area as the wall is moved farther away?