Laser beams are sometimes used to burn away cancerous tissue. What is the intensity, in watts per square meter, of a laser beam that is 90.0% absorbed by a 1.95-mm diameter spot of cancerous tissue and must deposit 480 J of energy to it in a time period of 4.05 s?

Explanation:

1.95 mm = 0.00195

Suppose the cancerous tissue has a circular shape with area of

The actual energy output of the laser beam with 90% efficiency is

The power of this energy over 4.05 s time period per square meter is

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2

i already answered it by 34/s