Page 69 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

Daniel cell: It is a modification of simple voltaic cell, because it is similar in chemical action. It was the first cell in
which a depolariser was used to avoid polarisation and amalgamated zinc road for preventing local action.

Construction
This cell consists of an outer copper vessel, which serves as positive electrode. This vessel contains concentric
solution of copper sulphate, act as the depolariser. (this solution keep saturated by placing of crystal copper
sulphate). In side this vessel is a porous pot containing dilute sulphuric acid as electrolyte and amalgamated zinc
rod- act as negative plate.
The chemical reaction inside the porous pot may be represented as follows;
Zn +H SO 4 ZnSO + 2H
++
2
4
The chemical reaction outside the porous pot is;
2H + CuSO H SO +Cu ++
4 2 4
In this manner polarisation is prevented.
The EMF of the cell is1.12v and internal resistance varies from 2 - 6ohm.
Advantages
• It is cheap and gives constant voltage

• So used in laboratories for experiment.
Leclanche cell
Construction
This cell consists of a glass jar contain solution of ammonium chloride (NH Cl) as the electrolyte and amalgamated
4
zinc immersed it, as negative plate (fig) the fig also shows a porous pot containing a carbon rod as positive plate.
This pot is typically packed with manganese dioxide(MnO ) act as polariser and powdered carbon particles,
2
serves as a conductor. A hole is provided at the top of porous pot for the gases escaping during chemical action.

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CITS : Power - Electrician & Wireman - Lesson 13-19