The variation of terminal voltage ( V ) versus current ( I ) drawn from a cell is plotted as a straight line. The graph intersects the voltage axis at 10 V and the current axis at 5 A . If this cell is connected across an external resistor of 3 , what will be the terminal voltage across the cell?

Step-by-step solution

From the given V-I graph description, the intercept on the voltage axis represents the emf ( E ) of the cell (when I = 0 ). Thus, E = 10 V The intercept on the current axis represents the maximum current or short-circuit current ( I_ ) when the terminal voltage is zero. I_ = E r = 5 A Internal resistance r = 10 5 = 2 When the cell is connected to an external resistor R = 3 , the current in the circuit is: I = E R + r = 10 3 + 2 = 10 5 = 2 A The terminal voltage across the cell is the voltage drop across the externa