Magnets: Properties and Uses

Magnets: Properties and Uses

• Magnets are naturally occurring materials or man-made objects, typically composed of iron or steel, that attract certain metals.
• Natural magnets are often called lodestones or magnetite.
• Man-made magnets can be various shapes (U-shaped, horseshoe, bar, rod, ring, button).
• Magnets attract specific materials (magnetic materials) – iron, nickel, cobalt, and steel.
• Nails and paperclips are examples of magnetic materials.
• Magnets do not attract non-magnetic materials such as gold, silver, aluminum, copper, wood, paper, plastic, glass, and clay.

Magnet Characteristics

• Magnets have two poles: a north (N) pole and a south (S) pole.
• The strongest magnetic force is concentrated at the poles.
• Like magnetic poles (N-N or S-S) repel each other.
• Unlike magnetic poles (N-S) attract each other.
• Steel pins are attracted to both ends of a magnet.

Magnetic Force

• A force is a push or pull on an object that interacts with another.
• Force can change an object's motion (speed and direction), start it moving, stop it, change its shape, cause an object at rest to move.
• Friction is a force. It slows down or stops moving objects.

Uses of Magnets

• Magnets are found in many common electrical devices (telephones, speakers, headphones).
• Electromagnets, temporary magnets activated by electric current, are found in computers, and video recorders.
• Refrigerators use a magnet to close the door tightly.