Magnets and Magnetic Fields

Magnetic Forces

Force a magnet exerts on another magnet, on metal, or on moving charges.

Decreases with distance

All magnets have 2 magnetic poles, a north pole and a south poleForce is strongest at the polesLike poles repel, opposite poles attract.

Magnetic Fields

Surround magnets and exert magnetic forces.

Strongest at the poles.

Attract or repel another magnet or charge that enters the field.

Field lines begin at the north pole and move towards the south pole.

Magnetic Fields Around Magnets

Magnetic fields can be used to see how 2 magnets will interact.

If 2 magnets are lined up with the same poles facing each other, the magnetic field in between basically cancels out.

If 2 opposite poles are put next to each other, the magnetic field is strongest between them.

Like poles

Opposite poles

Magnetic Materials

Metals such as iron, nickel, and cobalt can become magnetic.

Each contain magnetic domains.

If the magnetic domains all face the same direction, the metal becomes magnetic – can make then align by using a magnet.

When they do not face the same direction, they are not magnetic.

ElectromagnetismMoving electric charges create a magnetic field.Direction of a magnetic field around a current carrying wire is determined by the “right hand rule.” Thumb points in direction

of current in wire. Direction your fingers curl

around is the direction of the magnetic field.

ElectromagnetsA solenoid is a coil of current-carrying wire that produces a magnetic field.

If you place a magnetic material like iron into a solenoid, the strength of the magnetic field increases.

The iron also becomes a magnet, called an electromagnet.

The strength of an electromagnet depends on 3 things. 1. The amount of current in the wire, more current = stronger magnet. 2. The number of loops, more loops = stronger magnet 3. Type of material put into coil, more magnetic properties, stronger

magnet

Solenoid with electric current

electromagnet