Experiment Description

Experiment

Experiment E09    Internal Resistance of a Cell

Objectives
  • Use of a multimeter to measure resistance
  • Study two graphical methods in determining the internal resistance of a home-made dry cell
  • Error treatment with a graph.
Description
In this activity, you will determine the internal resistance of a cell using two graphical methods: 1. Plot of V against I. 2. Plot of R against 1/I

In Experiment 1, you will verify the resistance marked on the resistance box with a multimeter.

In Experiment 2, you will vary the current drawn from a cell and measure its terminal voltage. A plot of V against I would be obtained.

In Experiment 3, you will vary the resistance of a circuit using a resistance box (which gives known resistance) and record the currents. From the data, the internal resistance of a cell can be estimated.
Apparatus
Dry cell with artificial internal resistance [1]
ammeter (1 mA, 10 mA, 100 mA, 1 A and 5 A) [1]
voltmeter (1 V and 5 V) [1]
rheostat (0 - 20 ohm) [1]
resistance box (0-1000 ohm in steps of 1 ohm) [1]
multimeter [1]
Experiment