Leclanché cell

4.2.2 Leclanché cell

The most common type of primary cell in use is the Leclanché cell. In its wet form, it consists of a glass jar containing:

1. a saturated solution of sal ammoniac (ammonium chloride) as the electrolyte,
2. a zinc rod as the negative electrode, and
3. a plate of carbon as the positive electrode.

4.2.2.1 Wet Leclanché Cell

Wet Leclanché cell

A mixture of manganese dioxide and powdered carbon is pressed around the carbon rod and then enclosed in a porous pot which the solution can soak through. The manganese dioxide acts as the depolarizer, while the powdered carbon gives greater conductivity.

The e.m.f. of the Leclanché cell is 1.5 V and the internal resistance of a normal size cell is 1 Ohm. The wet cells are now going obsolete.  They were once a majorly used to supply power to land-line telephone installations in remote areas.