Simple Phenomena of magnetism

What are the two poles of a magnet?

North pole and south pole.

Magnetic Poles

The ends of a magnet where magnetic forces are strongest.

What happens when like poles meet?

They repel.

Repulsion

Force pushing two like poles apart.

What happens when opposite poles meet?

They attract.

Attraction

Force pulling a north and south pole together.

Magnetic Force

A non-contact force between magnetic poles.

What are uses of permanent magnets?

Compasses

Permanent Magnet

A magnet that produces its own magnetic field and does not lose magnetism.

Compass

Instrument using Earth’s magnetic field; needle always points north.

What are uses of electromagnets?

MRI scanners

Electromagnet

A magnet created when current flows through a coil.

Mag-Lev Train

Train that levitates using magnetic repulsion to reduce friction.

Which metals are magnetic?

Iron

Magnetic Materials

Materials attracted to magnets; respond to magnetic fields.

Non-Magnetic Materials

Materials not affected by magnets.

How can you tell if something is a magnet?

If it is repelled by a known magnet.

What is a permanent magnet?

A magnet that keeps its magnetism and creates its own field.

Permanent Magnet Material

Typically steel.

What is an induced magnet?

A material that becomes magnetic only when in a magnetic field.

Induced Magnetism

Temporary magnetism caused by placing material in a magnetic field.

What happens when a magnetic material is brought near a magnet?

It is always attracted.

Soft Iron

Material that magnetises easily and demagnetises quickly.

Why does the induced pole form opposite to the magnet’s pole?

Opposite poles attract.

What happens when induced magnet is removed?

It loses magnetism quickly.

What is a magnetic field?

Region where a magnetic pole experiences a force.

Magnetic Field Lines

Lines showing direction and strength of magnetic field.

Direction of Magnetic Field

From north pole to south pole.

Where is magnetic field strongest?

At the poles (lines are closer together).

How do field lines show strength?

Closer lines = stronger field; spaced lines = weaker field.

What happens between two attracting magnets?

Field lines link smoothly between opposite poles.

What happens between two repelling magnets?

Field lines push apart between like poles.

How do you show magnetic field direction on diagrams?

Arrows from north to south.

What are two methods to plot magnetic fields?

Iron filings or plotting compasses.

How do you use iron filings to show magnetic fields?

Sprinkle filings on paper over magnet and tap gently.

Iron Filings

Small pieces of iron that align with magnetic fields.

How do you use a plotting compass to draw field lines?

Move compass dot by dot

Plotting Compass

A small magnetic needle showing field direction.

Procedure for plotting field lines with compass

Place compass at dot, mark new dot, move, repeat, and connect dots.

Why does compass arrow point from north to south?

Because the north end of compass points toward magnetic south pole.

Field Line Rule

Always draw numerous smooth curves from north to south.