An electric cell is source of electrical energy. The cell gives dc current. The emf developed and current supplied by a cell is very small. The electrical energy can be stored in cell.
Definition of Electric Cell
A cell is source of emf in which chemical energy is converted into electrical energy.
- An electric cell basically consists of two electrodes of different material, so that different potentials are built up when chemical action takes place on them.
- An electrolyte such as an acid, alkali or salt solution so that chemical action takes place between two electrodes. The solution must be capable to react chemically with the two electrodes.
- When two electrodes are immersed in the electrolyte, due to chemical action between electrodes and electrolyte, a potential difference established between two electrodes.
E.M.F developed in a Cell
The magnitude of emf developed in cell depends upon the following.
- Nature or material of the plates used as electrodes of the cell.
- Type of the electrolyte used in the cell.
Types of Cells
Electric cells can be divided into two types.
The cell in which chemical action is not reversible, called primary cells. Voltaic cell, Daniell cell, Silver Oxide cell, Dry cell etc are the examples of Primary Cell.
In these types of cells, once the cell discharge,it cannot be recharged because chemical action, in this case, is not reversible and the cells cannot be recharged. This makes Primary cells expensive source of electrical energy and that is why these cells are rarely used in commercial applications.
The cell in which chemical action is reversible, called secondary cell. Lead acid cell, Nickel-iron alkaline cell, etc are the examples of secondary cells. These cells are rechargeable. In these cells, chemical action is reversible and cells can be recharged. While recharging, electrical energy is converted in the cell itself.