A solar cell generates apotential difference of 0.10 V when a 400 resistor is co
ID: 1675387 • Letter: A
Question
A solar cell generates apotential difference of 0.10 V when a 400 resistor is connectedacross it, and a potential difference of 0.15 V when a 1000 resistoris substituted. (a) What is the internal resistance of thesolar cell? 1Your answer is incorrect. (b) What is the emf of the solar cell? 2 V (c) The area of the cell is 3.0cm2, and the rate per unit area at which it receivesenergy from light is 2.0 mW/cm2. What is the efficiencyof the cell for converting the light energy to thermal energy inthe 1000 external resistor? 3%Explanation / Answer
consider the emf of solar cell be ? and the output voltage be V . thus
V = ? - i r
= ? - ( V / R ) r
potential difference of 0.10 V when a 400 resistor is connected across the solar cell
0.1 V = ? - ( 0.1 V / 400? ) r .......(1)
potential difference of 0.15 V when a 1000 resistor is connected across the solar cell
0.15 V = ? - ( 0.15 V / 1000? ) r ..........(2)
on solveing equations (1) and (2)
a) internal resistance r = 500 ?
b) emf of the solarcell is ? = 0.225 V
c) received energy from light is P received = 3.0 mW/cm2
= ( 3.0 mW/cm2 ) ( 2 cm 2 )
= 6 mW
efficiency of the cell
? = ( 0.15)2 / 1000 * 6*10-3 W
= 3.75*10-3
= 0.375 %
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