Q. A straight line plot showing the terminal potential difference (V) of a cell as a function of current (I) drawn from it, is shown in figure. The internal resistance of the cell would be then
(i) 2.8 ohms
(ii) 1.4 ohms
(iii) 1.2 ohms
(iv) zero
Answer: (i) 2.8 ohms
I = 0, V = E, ∴E = 5.6 V
r=E/I= 5.6/2.0 = 2.8 ohms