How Electromagnetic Coils Work

Tag : toroidal coils
In order to understand the workings of inductors, one must firstimagine a simple electrical circuit consisting of an incandescentlight bulb connected in parallel to an inductor. This circuit ispowered through a battery also connected in parallel to the lightbulb through a switch. Let's say we hit the switch. Common sensetells us that because the coil has a lower electrical resistancethan the light bulb, it will act as a short circuit and prevent thelight bulb from emitting light.

However, the reality is very different. When the switch is turnedon, the light bulb burns brightly at first before dimming to alower light intensity. The same effect takes place when the switchis turned off, only that after experiencing high brightness thelight bulb stops emitting light completely.

This is due to inductance. When current starts flowing through thecoil it generates a magnetic field that tries to stop the currentfrom flowing through the coil by generating a second current but inopposite direction. Albeit, when the magnetic field is established,the current flow goes back to normal. Alternatively, when thecurrent flow is stopped, the magnetic field tries to compensate inorder to maintain it by generating electric current through thecoil. By doing so the magnetic field can no longer be sustained andcollapses, keeping the light bulb lit for just a small amount oftime.

Inductance capacity

The inductance of an electromagnetic coil is measured in Henries after the American scientist Joseph Henry who discoveredelectromagnetic induction roughly at the same time as MichaelFaraday. The inductance of a coil is calculated using an equationinvolving the number of turns, the properties of the coil core air, vacuum, iron, etc. - the cross section of the turns and coillength.

Electromagnetic coils are generally used either to generatemagnetic fields or as inductors inside electronic oscillators andcan be found mostly anywhere around an electric or electronicdevice.