# Electromagnetism. Magnets Magnets are materials that produce a magnetic field. Magnets can only exert a force on some metals ( iron, cobalt and nickel)

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Electromagnetism

Magnets Magnets are materials that produce a magnetic field. Magnets can only exert a force on some metals ( iron, cobalt and nickel) and each other.

A magnet has a magnetic field around it where the magnetic forces act.

A magnetic field exerts a force on other magnets and any object that has a magnetic field.

A magnet also attracts iron objects and other similar objects that are made of metal.

The atoms in a magnet are aligned according to their magnetic poles.

The magnetic force of a magnet is strongest at its poles.

The south pole of the magnet attracts the north pole and the north pole attracts the south pole. Like repels like Unlike attracts unlike

When you break an iron magnet into two or more pieces you get more magnets that have both north and south ends.

A permanent magnet is one that keeps its magnetic properties for long periods of time.

Compass Needle A magnet that is free to rotate when placed in a magnetic field. North pole of the compass bar magnet will point towards the south pole of a bar magnet.

Earth’s Magnetic Field The Earth acts like a giant bar magnet. North Pole of the compass needle points north. On Earth, its South magnetic pole is near it’s geographic North Pole. One theory says that the Earth’s magnetic field is caused by circulation of molten iron and nickel in the Earth’s core.

Using a magnet to make electricity Electromagnetic Induction is the process of producing an electrical current by moving a loop of wire through a magnetic field.

Using electricity to make a magnet An Electromagnetic magnet is one in which the magnetic field is produced by electric current. The magnetic field disappears when the current is turned off.

You can make a temporary electromagnet by wrapping a wire around an iron core.

Increasing the current increases the strength of the electromagnetic force. The direction of the field depends on the direction of the current.

If more loops are added, the field lines overlap and become stronger. If an iron core is inserted into the coil, the iron becomes magnetized.

Magnetic properties of Electromagnets can be controlled by changing the electric current. They are used in stereo speakers and electric motors and to lift large objects.