Magnetism and Electromagnetism

Magnets and Electromagnetism Georgia Performance Standards SPS10. Students will investigate the of properties electricity and magnetism. c. Investigate applications of magnetism and/or its relationship to the movement of electrical charge as it relates to electromagnets simple motors permanent magnets

How were magnets discovered? Magnetite/Lodestone = naturally occurring mineral Could pick up metallic objects If floated on water, it would always orient itself in the same direction

The magnetic force… (notes) Is an interaction between two magnets can even be felt before magnets touch gets stronger as the magnets get closer

What is a magnetic field? (notes) a field that surrounds a magnet and exerts magnetic force connects the north and south poles of a magnet together

How do magnets interact? (notes) opposite poles (N,S) attract each other like poles (N, N or S,S) repel each other

Earth is a giant magnet Earth’s geographic north pole (GNP) is its magnetic south pole (MSP) the “north” needle on a compass points toward the GNP because it’s really the MSP!

What makes something magnetic? (notes) magnetic domain = groups of atoms with aligned magnetic poles -- unaligned magnetic domains = nonmagnetic -- aligned magnetic domains = magnetic

How can magnets be “demagnetized?” (notes) How can magnets be “demagnetized?” heating jarring hitting dropping both cause the magnetic domains to move around and become unaligned

demagnetized magnets can be re-magnetized by exposing them to a very strong magnetic field

What happens if you cut a magnet in to 2 pieces? (notes) What happens if you cut a magnet in to 2 pieces? S N break in two S N S N

What is an electromagnet? (notes) What is an electromagnet? Temporary magnet Made by placing a piece of metal inside a current-carrying wire Temporarily aligns magnetic domains

Benefits of Electromagnets (versus Permanent Magnets) How can the strength of an electromagnet be increased? 1. add more coils of wire 2. increase the electric current through the wire Benefits of Electromagnets (versus Permanent Magnets) Turn on and off Control the strength

Examples of Ways Electromagnets are used are… Look at the following slides and know how each work… especially the relationship between the permanent magnets and electromagnets to make it move (if they have them…) What are the two main parts of an electric motor? Permanent magnet and electromagnet.

galvanometer

magnets

It is possible to… (notes) produce an electric current by moving a loop of wire through a magnetic field This is called ELECTROMAGNETIC INDUCTION. Main example of Electromagnetic Induction in action is a generator: produces electricity by rotating a coil of wire in a magnetic field Other Examples of Uses: Hydroelectric dam, windmill, shake flashlight, winding flashlight