# Magnetism

## Physical Science - Middle School

1
/
2
Earth as a Magnet © Copyright NewPath Learning. All Rights Reserved. 94-4808 www.newpathlearning.com The needle on a compass is magnetized. It aligns itself with the Earth’s magnetic fields and will usually point toward the magnetic north pole. If a compass is placed near an electric current, the needle may not accurately point north because the electricity itself creates a magnetic field. coils wire iron core switch current from battery + ALKALINE BA TTER Y generator coil of wire iron core magnetic field Attract Repel The Earth acts like a giant magnet. While the magnetism of the Earth is difficult to explain, there is no question that the Earth has two opposite poles and a strong magnetic field. The Earth has a geographic north and a south pole and it also has a magnetic north and a south pole. N S Magnetic North Magnetic South North Pole magnetic field South Pole S N N S S N N S N S N S N S N S N S Properties of Magnets A magnet is any substance that attracts the element iron or anything with iron in it. All magnets have opposite ends or poles. These are referred to as the north (N) and south (S) poles. Because similar poles repel each other and opposite poles attract each other, magnets can either repel or attract each other. The degree to which they do this depends on the magnetic force of the magnet. In addition, because of polarity, all magnets will point toward the magnetic north pole of the Earth. Magnetic Fields While the greatest magnetic force is at the poles, there is some degree of magnetism all around a magnet. This is called the magnetic field. It is the space around a magnet where magnetic materials are affected by forces, and so may be attracted or repelled. Magnetic field lines are invisible lines that map the strength of the magnetic force around the magnet. The closer together the field lines are, the stronger the magnetic force is. Electromagnetism Electromagnets A magnetic field is produced when an electric current flows through a coil of wire. This relationship between electricity and magnetism is called electromagnetism. The magnetic field around an electromagnet is similar to the one around a bar magnet. Unlike bar magnets which are permanent magnets, the magnetism of electromagnets can be controlled by switching on or off the electric current. Electromagnets are used in many devices including electric motors, loudspeakers, and electric doorbells among many others. Electricity from Magnetism When a magnet moves through a coil of wire or when a wire moves between the poles of a magnet it changes the magnetic field and generates an electric current. The process of creating an electric current by changing a magnetic field is called electromagnetic induction. An electric generator uses electromagnetic induction to change mechanical energy into electrical energy. Magnetism
Earth as a Magnet © Copyright NewPath Learning. All Rights Reserved. 94-4808 www.newpathlearning.com iron core current from battery + ALKALINE BA TTER Y The Earth acts like a . While the magnetism of the Earth is difficult to explain, there is no question that the Earth has two and a strong . The Earth has a geographic and a pole and it also has a magnetic north and a south pole. N S Magnetic North Magnetic South North Pole magnetic field South Pole S N N S S N N S N S N S N S N S N S Properties of Magnets A _______________ is any substance that attracts the element iron or anything with iron in it. All magnets have opposite ends or _______________ . These are referred to as the _______________ and _______________ poles. Because similar poles _______________ each other and opposite poles ______________ each other, magnets can either ______________ or ______________ each other. The degree to which they do this depends on the ____________ ____________ of the magnet. In addition, because of ______________ , all magnets will point toward the magnetic north pole of the Earth. Magnetic Fields While the greatest ____________ ___________ is at the poles, there is some degree of magnetism all around a magnet. This is called the _____________ ____________. It is the space around a magnet where magnetic materials are affected by forces, and so may be attracted or repelled. Electromagnetism Describe: Electricity from Magnetism What are magnetic field lines? _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ What are magnetic field lines? ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ Electromagnetism: ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ Electromagnet: ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ Key Vocabulary Terms attract electric current electric generator electrical energy electromagnet electromagnetism magnet magnetic field mechanical energy north pole pole repel south pole Magnetism \|xiBAHBDy01819tz]