Q9 of 40 Page 1

Write the name of the cell which is generally used in hearing aids. Write the reactions taking place at the anode and the cathode of this cell.

Mercury cell is generally used in hearing aids (an ear machine for the deaf person). This is a newer type of dry cell which has found use in low current devices.


Mercury cell consists of zinc container as anode (positive part), a carbon rod as cathode (negative part) and a paste of mercuric oxide mixed with KOH as the electrolyte. A lining of porous paper keeps the electrolyte separated from the zinc anode.


The cell produces electrical energy by the following reaction:



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