A typical photovoltaic cell delivers 3.8×10−3 {\rm W} of electric energy when illuminated with 0.14 {\rm W} of light energy.

Question

what is the energy efficiency of the cell?

Answer 1

you put 1.4 *10^-1 in
you get 3.8*10^-3 out
in percent that is
3.8^10^-3 * 10^2/1.4*10^-1
= (3.8/1.4) 10^0
= 2.7 percent

Answer 2

thanks