A 0.75-mW laser emits a narrow beam of light that enters the eye, as shown in the figure.
(a) How much energy is absorbed by the eye in 0.2 s?
(b) The eye focuses this beam to a tiny spot on the retina, perhaps 6.0 m in diameter. What is the average intensity of light (in W/cm2) at this spot?
(c) Damage to the retina can occur if the average intensity of light exceeds 1.0 x 10-2 W/cm2. By what factor has the intensity of this laser beam exceeded the safe value?