Potentiometer is usually defined as a three-terminal resistor. This instrument has been generally appped for measuring the production of an adjustable voltage spanider while rolpng or spding contact. The primary apppcation of the Potentiometer is for the determination of the internal resistance of primary cells. In accordance with the theory of Thévenin, the power source can be acknowledged as a voltage source that can be ideal in series with impedance, usually termed as internal resistance.

Aim

The main of this experiment is to determine the internal resistance of a given primary cell with the help of a potentiometer.

Required apparatus

Among the required apparatus, the first requirement is a galvanometer. Voltameter, and potentiometer. The other requirements include a fractional resistance box, one battery, wires for the connection formation, and sandpaper (Batteryuniversity, 2022). Along with that, one must require two numbers keys that are of one way and one Leclanche cell. A jokey and one set square is required as well.

Principle

In order to conduct the experiment, it needs to be conjectured that a resistance that is represented by the letter R is connected across the e.m.f of a cell. The internal resistance of this cell is represented by the letter r. Based on this, the current of the circuit that is I will be equivalent to the E = I(R+r) that can be represented as the ratio of E and R+t, which will be equivalent to I (Ncert, 2022). This mathematical representation of the theory leads to get the equation that is V = IR = E - Ir or r= (E/V -1)R.

In addition, it can be conjectured that the distance between the balance null points from the end A is l0 whereas l will be representative of the difference between the open and closed circuit of the potentiometer (Castaño et al. 2018). In such a case, the E will be proportional to l0 and the l will be proportional to V. Therefore, the formed equation of this experiment can be mathematically represented as r= (l₀-l/l) R.

Circuit diagram