To determine the internal resistance of a given primary cell by using potentiometer | Physics Practical Class 12

 To determine the internal resistance of a given primary cell by using potentiometer.

Aim: -

To determine the internal resistance of a given primary cell by using potentiometer.

APPARATUS: -

A 10 wire potentiometer, Leclanche cell, two resistance box, two one way key, 2 volt battery/battery eliminator, galvanometer, connecting wires.

THEORY: -

Write only formula and describe it.

OBSERVATIONS: -

1.    Potential drop across the battery, B = ...........................

2.    Potential drop across the cell E = .................... (B > E)

Table for internal resistance of a cell

CALCULATIONS: -

1.    Calculate r for each reading in above tabel.

2.    Find the mean value of internal resistance "r" from the table.

RESULT: -

The internal resistance of the cell is r = ....................... ohm.

PRECAUTIONS: -

1.    Connections should be tight and neat.

2.    Ammeter reading should remain constant for a pair of reading.

3.    Jockey should be pressed gently over the wire.

4.    Readings should be taken over the entire length of the wire.

5.    Null point should be identified carefully.