Salt bridge is a U- tube containing electrolyte like KCl, KNO3 etc in semi- solid agar. It connects two half cells. The main uses of salt bridge are:
- Salt bridge maintains the electrical neutrality of each half cell
The transfer of electrons from Zn anode to Cu cathode develops excess +ve ions in ZnSO4 solution due to Zn2+ ions and excess -ve ions in CuSO4 solution due to SO42- ions which are neutralized by Cl- and K+ of salt bridge.
- Salt bridge maintains the flow of current by completing the circuit
The circuit is completed externally by conducting wire for flow of current and internally by salt bridge for flow of ions.