Question

Why do galvanic cells need a salt bridge?

Answer 1

The purpose of a salt bridge is not to move electrons from the electrolyte, rather to maintain charge balance because the electrons are moving from one half cell to the other.

Without the salt bridge, the solution in the anode compartment would become positively charged and the solution in the cathode compartment would become negatively charged,because of the charge imbalance,the electrode reaction would quickly come to a halt,therefore It helps to maintain the flow of electrons from the oxidation half cell to a reduction half cell.