Electromagnetics

=**Electromagnets**=


 * Electromagnetism** is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation. Electromagnetism is the force that causes the interaction between electrically charged particles.

When current flow through a wire, it gives an interesting characteristic-a magnetic field is created.



In the diagram above, when conventional current flows in the direction aligned with the arrow, a magnetic field, B, is induced in a clockwise manner, relative to the direction of the current.

An electromagnet is usually made from a coil of wires, wound in the same direction. When they are placed side by side, the magnetic fields interact with each other and forms a strong electromagnet.

In the diagram above, conventional current flows through the wire coil, and a field is induced. The left side of the coil becomes a North pole (N) and the right side of the coil becomes the south pole.

Flemming's right-hand grip rule
To make it easy for use to predict the field that is going to be induced, there is such thing as the right-hand grip rule:

To put it simply, the thumb indicates on which end the North pole will be and the fingers that are "coiled" simply refers to which direction the wires are coiled; clockwise or anti-clockwise.

Making an electromagnet stronger
There are several factors that affects the magnetic field induced, namely:

> //Explanation:// More turns of wire means that the coil will generate a greater amount of magnetic field force (measured in amp-turns!), for a given amount of coil current. > > //Explanation:// Greater coil area presents less opposition to the formation of magnetic field flux, for a given amount of field force (amp-turns). > > //Explanation:// A longer path for the magnetic field flux to take results in more opposition to the formation of that flux for any given amount of field force (amp-turns). > > //Explanation:// A core material with greater magnetic permeability results in greater magnetic field flux for any given amount of field force (amp-turns). >
 * **NUMBER OF WIRE WRAPS, OR "TURNS" IN THE COIL:** All other factors being equal, a greater number of turns of wire in the coil results in greater inductance; fewer turns of wire in the coil results in less inductance.
 * **COIL AREA:** All other factors being equal, greater coil area (as measured looking lengthwise through the coil, at the cross-section of the core) results in greater inductance; less coil area results in less inductance.
 * **COIL LENGTH:** All other factors being equal, the longer the coil's length, the less inductance; the shorter the coil's length, the greater the inductance.
 * **CORE MATERIAL:** All other factors being equal, the greater the magnetic permeability of the core which the coil is wrapped around, the greater the inductance; the less the permeability of the core, the less the inductance.