Problem 1: Compute the power densities for the medically realistic situations described below:

(a) Photocoagulation of the retina using 500μm-diameter spots and a laser power of 200 milliwatts.
(b) Photovaporization of opacities within the eye using 50μm-diameter spots and laser power setting of 2 watts.
(c) Compare these two power densities by computing the ratio between them, and explain why your answer makes physical sense given the uses to which the lasers are applied.

An initially unpolarized light if intensity 500 w/m^2 passes through four polarizers. the transmission axis between adjacent polarizers is 45∘. what percentage of the initial intensity is transmitted by the system?

Apair of 10μf capacitors in a high-power laser are charged to 1.7 kv.a. what charge is stored in each capacitor? b. how much energy is stored in each capacitor?

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do an amount of work of 79.0 j when you compress the springs a distance of 0.230 m from their uncompressed length. (a) what magnitude of force must you apply to hold the platform in this position? (b)how much additional work must you do to move the platform a distance 0.230 m farther? (c) what maximum force must you apply to move the platform a distance 0.230 m farther?