A laser blackboard pointer delevers 0.10-mW average power in a beam 0.90 mm in diameter.
a) Find the average intensity.
b) Find the peak electric field.
c) Find the peak magnetic field.
The Attempt at a Solution
ok for part a) i used the formula ave. s = p/4 pie r^2 (as p=.10 mW and r=0.45 mm)
but i didnt get the right answer
so am i using the wrong formula or the wrong value for r?
for part (b) and (c) i cant do anythin bout it cuz i need the average intensity
in order to find the elecric and magnetic fields.
somebody plez help me asap....thanx!!