Magnetism

Introduction

To a child, magnets can be the most fascinating of play things. Honestly, magnets are still as fascinating to many adults. Two magnets can be seen to affect each other at a distance, without making contact. Depending on how you arrange them, they may attract or repel. With advances in technology we've been able to create what are referred to as 'rare earth' magnets that can easily be held in the hand and are strong enough to break bones if they are allowed to snap together. But magnets are more than just possibly dangerous toys. In 1820, a physicist named Hans Christian Ørsted showed that magnets were not limited to certain types of metal found on the ground. Current carrying wire can produce a magnetic field as well. This discovery led to the creation of devices like electric motors and speakers. In this unit we'll see how magnets work and how they are used in some of the most useful and common devices today.

Essential Questions

How does a magnet's permeability affect its ability to maintain its magnetic properties?
How does a coil's magnetic dipole moment affect the torque on the coil when the coil is in an external magnetic field?
How do magnetic domains affect the magnetism of an object?
How does a moving electric charge interact with an external magnetic field?

Key Terms

Magnet - A material or object that produces a magnetic field.
Magnetic domain - A group of atoms whose magnetic fields are aligned in the same direction and act, themselves, as magnets.
Magnetic field - A region in which a magnetic force can be detected. It is visualized by the use of magnetic field lines.
Magnetic dipole - Because all magnets have two poles, they are considered dipoles.
Compass - An instrument for determining direction relative to Earth's magnetic poles.
Magnetic permeability - The measure of the ability of a material to support the formation of a magnetic field within itself.
Solenoid - A long, helically wound coil of insulated wire.
Electromagnet - A temporary magnet whose magnetic field is produced by an electric current.
Magnetic dipole moment - A quantity that determines the force a magnet can exert on electric currents and the torque that a magnetic field will exert on the magnet.
Electric motor - A machine that converts electrical energy to mechanical energy.

IMAGES CREATED BY GAVS