Chapter 16, Problem 71PE

Medical Application

(a) What is the intensity in $\text{W}/{\text{m}}^{\text{2}}$ of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 500 J of energy into a circular spot 2.00 mm in diameter in 4.00 s? (b) Discuss how this intensity compares to the average intensity of sunlight (about $\text{7}00\text{ W}/{\text{m}}^{\text{2}}$ ) and the implications that would have if the laser beam entered your eye. Note how your answer depends on me time duration of the exposure.