Electromagnetism - Part 1

Salaam! (Peace!)

Well, today we are going to discuss the A2 Physics topic: Electromagnetism
In this first part, we'll discuss Magnetic Fields which is a sub-topic of this chapter.

As we all know from O level work, magnetic fields have field lines similar to electrical fields. These lines do not cross each other. The closer they are, the higher the strength of the magnetic field. The field lines move in the direction of north to south. From the north pole of the magnet to the south pole of the magnet. To get a good idea, you could use iron fillings on a piece of paper with a magnet at the bottom to literally see the magnetic field of that magnet. you can also use a plotting compass to find its direction. All that is easy right? I hope you all are familiar with the magnetic field line diagrams of a straight wire, a solenoid, and a flat coil.

You must first know that if there is a uniform magnetic field in one direction, and a current running perpendicular to that magnetic field, the force exerted on that current carrying wire will be perpendicular to both the current and the magnetic field. This is known as the Motor Effect. To find the direction of the force, use Flemming's Left-Hand Rule. Where your middle finger represents the direction of the current, the fore finger the direction of the magnetic field, and the thumb as the direction of the force exerted on the wire.

As physics is the study of measurements, techniques have been derived to measure these magnetic fields.First up is the Magnetic Flux Density which is measured in the unit called Tesla.
The force that acts on a wire due to the motor effect was found to be directly proportional to the current in the wire and the length of the wire which is present in the magnetic field.
So:  F = BIL where B is the constant of proportionality known as the magnetic flux density.

An important definition:
One Tesla is the uniform magnetic flux density which, acting normally to a long straight wire carrying a current of 1 Ampere, causes a force per unit length of 1 N/m on the conductor.