A 15mw energy laser has a beam exit diameter of 2cm and beam divergence of 0.0002radians.
a) Calculate the power density of the beam at 100meters away from the source.
b) Assuming that this beam has a wave length of 312nm, and the viewing time is 10minutes/day, determine if the TLV is exceeded.
After 7 hours of its preparation determine the portion left of a radioactive isotope, if its half-life is known to be 5 hours.