Magnets

Magnet Activity #1

What will move a magnet? Test the items listed below to see if they can make the magnet move. The next slide will reveal the answers.

ButtonNickel

Nuts & BoltsScissorsMarblePennyPaper ClipPencil

NoYesItem

What will make a magnet move?

Button

Nickel

Nuts & Bolts

Scissors

Marble

Penny

Paper Clip

Pencil

NoYesItem

Paper clips

attract...

because they are made of

iron.

Scissors attract.

because they are made of

iron.

Nuts and bolts attract.

because they are made of

iron.

Magnets in my house

Refrigerator magnets

Headphones

Telephone receivers Phone ringers

Seal around refrigerator door

Credit card magnetic strip

Computer monitor, hard drive, speakers

Shower curtain weights

Power supply transformersTV deflection coil

Microwave tubes

• Caused by electron spin

• An object in which all domains are aligned in the same direction

• Composed of ferromagnetic material (iron, nickel, cobalt, gadoliniuim).

What is a magnet?

What are magnetic domains?Magnetic substances like iron, cobalt, and nickel are composed of small areas where the groups of atoms are aligned like the poles of a magnet. These regions are called domains. All of the domains of a magnetic substance tend to align themselves in the same direction when placed in a magnetic field. These domains are typically composed of billions of atoms.

Magnetized ObjectsUnmagnetized Magnetized

For every North, there is a SouthIf you take a bar magnet and break it into two pieces, each piece will again have a North pole and a South pole. 

S N S N S N

No Monopoles Allowed - It has not been shown to be possible to end up with a single North pole or a single South pole, which is a monopole

S N

a material that is easily magnetized and

loses its magnetism quickly

Temporary Temporary MagnetMagnet

VS Permanent Permanent MagnetMagnet

materials that are hard to magnetize and

will also stay magnetized for a long

time

Magnetic Field LinesMagnetic field lines can be drawn in the direction a

north pole of a compass needle would point if placed at that point. The number of lines per area

show the strength of the field at that point.

Uses of magnets

• Magnets were first put to use in navigation because they always point north and south.

• Magnets are used to hold, separate, control, convey and elevate products and to convert electrical energy into mechanical energy or convert mechanical energy into electrical energy.

Ways to demagnetize a magnet

1.) Strike the magnet with force

2.) Heat it

The earth is like a giant magnet!

The nickel iron core of the earth gives the earth a magnetic field much like a bar magnet.

We use the Earth’s magnetic field to find direction.

The needle of a compass always points toward the magnetic south pole.

We call this direction “North” (remember, opposites attract)

Activities #2 - #4

Supplement – What is in your breakfast

Electricity and Magnetism – how are they related?

1.) When an electric current passes through a wire a magnetic field is formed.

2.) when a wire is moved across a magnetic field, an electric current is induced in the wire

Demos & Activities

Magnet from electricity

• ELECTROMAGNET

Electricity from magnets

• ELECTRICAL INDUCTION

See Activity #4

In general, who has a better sense of direction?

1. Males

2. Females

Fun FactHumans have a small number of very tiny iron filings in the bone and cartilage of the nose, right in the center near the eyes. There is evidence that people can use these filings to orient themselves toward magnetic north even when blindfolded. MALES tend to have more of these filings, which explains why males tend to be better at geographic orientation (and why females tend to rely more on street names and other identifiable features).

http://www.youtube.com/watch?v=wOv0AkphLhE

Fun with Magnets