Question

In full sunlight, a solar cell has a short circuit current of 75mA and a current of 70mA for a terminal voltage of 0.6 V with a given load. The Thevenin resistance of the solar cell is

• A. 8$\Omega$
• B. 8.6$\Omega$
• C. 120$\Omega$
• D. 240$\Omega$

Answer 1

The correct option is C 120$\Omega$


Let the given load is Z.

Then the current,

$I=\frac{Z_{eq.}}{Z+Z_{eq}}\times I_{SC}$ ...(i)

Given, I = 70mA, $I_{sc}=75mA,v_{AB}=0.6V$

From equation (i),

$70=\frac{Z_{eq.}}{Z+Z_{eq}}\times 75$

$\Rightarrow \frac{75}{70}=1+\frac{Z}{Z_{eq}}$

$\Rightarrow Z_{eq}=14\times Z$

and $V_{AB}=Z\times I$

0.6 = Z $\times$ 70 $\times$ 10${}^{-3}$

$\Rightarrow Z=\frac{600}{70}$

$\therefore Z_{eq}=14\times \frac{600}{70}=120\Omega$