Physics
posted by Krysten on .
At a spot in the ocean , the surface irradiance is 7.8*10^16 photons cm^2 s^1, and k=0.14 m^1. At what depth does the euphotic zone end? (Find definition for euphotic zone and solve for z)

Same idea as the last question but e^(.14 z)
and Io = 7.8*10^16
and you have to look up the irradiance for light to die out enough.
Once you do that, take the ln of both sides to solve it. 
From wikipedia:
"It extends from the atmospherewater interface downwards to a depth where light intensity falls to 1 percent of that at the surface (also called euphotic depth), "
so where I = .01 Io
or
I/Io = .01 = e^.14z
ln .01 = .14 z
4.6 = .14 z
solve for z