4.3 Voltage
and Current Capacity of Cells
The e.m.f.
of a cell depends on the materials of its electrodes and the electrolyte. On
the other hand, the amount of current an electric cell can produce in a given
span of time depends on the quality of electrodes and the electrolyte it is
made of.
The table below
shows the e.m.f. of some electric cells and the materials they are made of.
|
Cell
|
e.m.f.
|
Positive
Electrode
|
Negative
Electrode
|
Electrolyte
|
|
|
1
|
Simple
cell (Zinc-acid)
|
1.5
|
Copper
|
Zinc
|
Dilute
sulphuric acid
|
|
2
|
Leclanché
|
1.5
|
Carbon
|
Zinc
|
Sal
ammoniac
|
|
3
|
Mercury
|
1.35
|
Steel
|
Zinc
|
Potassium
hydroxide
|
|
4
|
Silver
oxide
|
1.5
|
Silver
oxide
|
Zinc
|
potassium or sodium hydroxide
|
|
5
|
Zinc
air
|
1.4
|
Oxygen
gas
|
Zinc
|
potassium hydroxide
|
|
6
|
Lithium
air
|
3.8
|
Oxygen
gas
|
Lithium
|
Organic
carbonate
|
|
7
|
Lead-acid
|
2.2
|
Lead
dioxide
|
Lead
|
Dilute
sulphuric acid
|
|
8
|
Nickel-cadmium
|
1.25
|
Cadmium
|
Nickel
hydroxide
|
Potassium
hydroxide
|
|
9
|
Lithium
ion
|
3.6
|
Lithium
cobalt oxide
|
carbon
|
Lithium
salt in organic solvent
|
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