A solar cell generates a potential difference of 0.10 V when a 500 Oresistor is connected across it, and a potential difference of 0.15 V when a 1000 Oresistor is substituted. What are the (a) internal resistance and (b) emf of the solar cell? (c) The area of the cell is 5.0 cm2, and the rate per unit area at which it receives energy from light is 2.0 mW/cm2.What is the efficiency of the cell for converting light energy to thermal energy in the 1000 Oexternal resistor?