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.

Asmall metal bar, whose initial temperature was 10° c, is dropped into a large container of boiling water. how long will it take the bar to reach 70° c if it is known that its temperature increases 2° during the first second? (the boiling temperature for water is 100° c. round your answer to one decimal place.) sec how long will it take the bar to reach 98° c? (round your answer to one decimal place.)

A3.9 g aluminum foil ball with a charge of +4.1×10−9 c is suspended on a string in a uniform horizontal e⃗ field. the string deviates to the right and makes an angle of 30∘ with the vertical. part a part complete what information about the e⃗ field can you determine for this situation? what information about the field can you determine for this situation? only the magnitude of e⃗ only the direction of e⃗ both the magnitude and the direction of e⃗ none of the above previous answers correct part b determine the magnitude of the electric field. express your answer with the appropriate units. e e = nothing nothing request answer part c determine the direction of the electric field. determine the direction of the electric field. to the right to the left away from you toward you

Name the non metal condut electricity