Chapter 28, Problem 23P

28.4 Lasers

(a) A laser pulse emits 2.0 J of energy during $\text{1}\text{.0 }\times {\text{ 10}}^{\text{-9}}\text{s}$. Determine the average power emitted during that short time interval. (b) Determine the average light intensity (power per unit area) in the laser beam if its cross-sectional area is $\text{8}\text{.0 }\times {\text{ 10}}^{\text{-9}}{\text{m}}^{\text{2}}$.