Question

(a) State the working principle of a potentiometer with help of the circuit diagram , explain how the internal resistance of a cell is determined.
How are the following affected in the potentiometer circuit when (i) the internal resistance of the driver cell increases and (ii) the series resistor connected to the driver cell is reduced ? Justify your answer. 5

Answer 1

(b) If the internal resistance of driver cell is increased then I given in the potentiometer circuit gets reduced.
Hence, balancing length of the potentiometer wire increases. When the series resistance to the driver cell is reduced then current I in the potentiometer circuit given by the driver cell increases. Therefore potential gradient in the potentiometer wire increases, hence, balancing length decreases.