Internal Resistance and Solar Cells

**Aryth** · January 22nd 2009, 12:13 PM

A solar cell generates a potential difference of 0.10 V when a 500 $\Omega$ resistor is connected across it, and a potential difference of 0.15 V when a 1000 $\Omega$ is substituted. What are the (a) internal resistance and (b)emf of the solar cell? (c) The area of the cell is 5.0 $cm^2$ , and the rate per unit area at which it receives energy from light is 2.0 $\frac{mW}{cm^2}$ . What is the efficiency of the cell for converting light energy to thermal energy in the 1000 $\Omega$ external resistor?

**vincisonfire** · January 22nd 2009, 12:49 PM

a) b) $\epsilon - R_{int}I = V$
$\epsilon = (R_{int}+R_{ext})I$
$\epsilon = V+RI = V+R\frac{\epsilon}{R_{int}+R_{ext}}$
$V= R_{ext}\frac{\epsilon}{R_{int}+R_{ext}}$
Solve for R and then for $\epsilon$