S.noTopicsPage No.

1Introduction1

2What is a cell?2

3Various Types of Cell3-4

4Measurement of Internal Resistance of a Dry Cell7

5Potentiometer8

6Experiment9-13

7Bibliography14

IntroductionWhat is the definition of internal resistance? The natural ohmic value of the electrodes in a battery. Internal resistance causes a batterys voltage to be lower with a load than without a load The opposition offered by the electrolyte of the cell to the flow of electric current through it is called the internal resistance (IR) of the cell Factors affecting internal resistance of a cell: Larger the separation between the electrodes of the cell, more the length of the electrolyte through which current has to flow and consequently the higher value of internal resistance Greater the conductivity of the electrolyte, lesser is the internal resistance of the cell i.e. internal resistance depends on the nature of the electrolyte The internal resistance of a cell is inversely proportional to the common area of the electrodes dipping in the electrolyte The internal resistance of a cell depends on the nature of the electrodes

What is a cell?The device which converts chemical energy into electrical energy is known as an electrochemical cell. Electric cell is a source of constant EMF but not constant current.

EMF of cell (E):

The potential difference across the terminals of the cell when it is not supplying any current is called its EMF.

Potential difference (V):

The voltage across the terminals of the cell when it is supplying current to external resistance is called potential difference or terminal voltage. Potential difference is equal to the product of current and resistance of the given parti.e. V=IR.