Question
A cell of emf ‘E’ and internal resistance ‘r’ is connected across a variable load resistor R. Draw the plots of the terminal voltage V versus (i) R and (ii) the current I.
It is found that when R = 4
, the current is 1 A and when R is increased to 9 
, the current reduces to 0.5 A. Find the values of the emf E and internal resistance r.
Solution
Plot for V vs. R 
Plot for V vs. I
Current in the circuit is given by,
