Induction Coil
This is an electrical device that is capable of producing a very high intermittent heat e.m.f by electromagnetic induction from a low voltage d.c source. E.g. battery.
The second e.m.f produced is large enough to spark between two terminals.

When a key is closed, current flows through the primary coil, and the core is magnetized. The soft iron armature is attracted so that the platinum contacts and the circuit is broken. At this point, the core loses its magnetism and the armature is pulled back by the spring so that contact can be re-established.
As the contact is made and broken repeatedly in the magnetic coil, changes in the magnetic flux take place and induce an e.m.f in the secondary coil which is sufficient to cause a spark jump across the gap
Ignition Coil
An ignition coil (also called a spark coil) is an induction coil in a car’s ignition system that transforms the battery’s voltage to the many volts needed to create and electrical spark in the spark plugs to ignite the fuel.
Uses of Ignition Coil
- It is used in ignition system of a motor car
- Operation of x-ray tube
- Mouse radio transmitter
The function of capacitor in ignition coil primary circuit is
- To control sparks at the platinum contact
- To promote rapid decay of magnetic flux at the break of primary circuit
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