How Do You Calculate Light Intensity After Passing Through Water?

[dobbinatrix]

I need to calculate the intensity of a 10000 lux light source traveling through 3.3 cm of water.

I have attempted to solve this using the equation I=I_oe^-A where i is the intensity, Io is the initial intensity, A is the absorbance calculated as the water attenuation coefficient times the depth, using the water attenuation coefficient of 0.23222 (this could be wrong?)

This equation can be simplified into I=I_o*10^-A
however when i plug my numbers into this i seem to get I=10000*9.9 which means that the intensity has increased tenfold in 3cm of water.
Somthing tells me I am wrong...

Any help would be greatly appreciated

P.S. thanks to ehild for last response

 

[ehild]

How could you get a number greater than 1 as the result for 10^(-A) (A>0)?

ehild