Magnets and Magnetic Fields

Magnets

Magnets possess a magnetic field and draw ferromagnetic materials towards them.
Every magnet has two ends, labelled as the North and South poles.
Attracting and Repelling are basic properties of magnets. They attract the opposite pole and repel the same pole.
Ferromagnetic materials are substances that can become magnetised, such as iron, cobalt, and nickel.
A magnet can induce magnetism in a ferromagnetic material, a process called magnetic induction.

A magnetic field is a region where magnetic force can be experienced. It is encircling a magnet.
Magnetic field lines are used to depict this field. They flow from north to south outside the magnet and from south to north inside.
The strength of a magnetic field is greatest at the poles and fades with distance.
The direction of the magnetic field at any point is the direction indicated by the north pole of a small test compass used to probe it.

An electric current passing through a wire generates a circular magnetic field around the wire.
The right-hand grip rule can be used to determine the direction of the field. Imagine grasping the wire with your right hand, with your thumb pointing in the direction of the current. Your fingers will curl in the direction of the magnetic field.
If the wire carrying the current is coiled into a loop, the magnetic field forms a pattern similar to a bar magnet. This is known as a solenoid.
The magnetic field strength, or magnetic flux density (B), around a solenoid can be increased by increasing the current or the number of turns per unit length, or by inserting a ferromagnetic core.

Electromagnetism is the interaction between electric currents or fields and magnetic fields.
An electromagnet is a type of magnet where the magnetic field is produced by an electric current. The magnetic field disappears when the current is turned off.
Electromagnets are commonly found in devices such as electric bells, relays, and circuit breakers.

A conductor carrying a current in a magnetic field experiences a force. This is called the motor effect.
The direction of the force can be determined by Fleming’s left-hand rule.
Factors affecting the magnitude of the force include: the magnitude of the current, the strength of the magnetic field, and the angle between the direction of the current and the direction of the magnetic field.

Electromagnetic induction happens when a change in magnetic field induces an electric current in a conductor.
It can be achieved by moving a magnet in and out of a coil of wire, or by spinning a coil of wire in a magnetic field.
The induced emf (electromotive force) can be increased by increasing the rate of change of the magnetic field, the number of turns on the coil, or the area of the coil.

Remember these principles to understand the concept of electricity, magnetism and their interaction in various physical phenomena. Happy revising!