Electric cells

Basic Introduction to Electric Cells

  • An electric cell is a device that is capable of converting chemical energy into electrical energy.
  • It consists of two electrodes: anode (negative electrode) and cathode (positive electrode).
  • These electrodes are immersed in a chemical solution known as the electrolyte.
  • When the cell is connected in a circuit, a chemical reaction takes place, which causes the flow of electricity.

Components & Functions of an Electric Cell

  • Anode: The electrode where oxidation (loss of electrons) occurs.
  • Cathode: The electrode where reduction (gain of electrons) occurs.
  • Electrolyte: The chemical substance in which an electric charge is carried by ions. This is present between the electrodes and facilitates flow of electrons.

The Chemical Reaction in Electric Cells

  • The chemical reaction inside the cell tends to force electrons to one electrode (creating an excess) and away from the other electrode (creating a deficit).
  • The electrode with electron excess gets a negative charge and becomes the anode, while the electrode with electron deficit gets a positive charge and becomes the cathode.
  • When a wire joins the anode and cathode externally (forming an electric circuit), electrons flow from anode to cathode through the wire, creating an electric current.

Types of Electric Cells

  • Primary cells: In these cells, the chemical reaction is irreversible. This means that they cannot be recharged once the chemicals have been used up. Examples include AAA, AA, C, D batteries and also button cells.
  • Secondary cells: These cells are built with chemical reactions that are reversible. They can be recharged and used multiple times. Examples are the batteries used in cars and mobile phones.

Factors Affecting the Electric Potential of a Cell

  • Nature of the Electrodes: Different materials used for electrodes can produce different potential differences.
  • Nature of the Electrolyte: Different electrolytes produce different amounts of potential difference.
  • Concentration of the Electrolyte: Higher concentrations can produce higher potential differences.
  • Temperature: The speed of the chemical reaction, and hence the cell potential, can be affected by temperature.