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Lesson · Grade 7 · Science

Magnets and Magnetic Fields

  • Grade 7
  • Science
  • 1 min 19 s
  • British Columbia
  • BC7-SC-22

A bar magnet builds up into one labelled diagram: its north and south poles, the invisible magnetic field around it, and the field lines that run from N round to S, crowded at the poles where the field is strong and spread out where it is weak. A compass then glides along a field line with its red end pointing along it, a steel clip is pulled onto the pole without being touched, and the video ends on the recap that a magnet has two poles and a magnetic field all around it, strongest at the poles.

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In one sentence

The question this lesson answers

What is a magnetic field? Let us look closely at a bar magnet.

Every magnet has two poles, a north pole and a south pole.

Transcript

What the lesson says

What is a magnetic field? Let us look closely at a bar magnet.

Every magnet has two poles, a north pole and a south pole.

We label them N and S. The two poles are always at opposite ends.

All around the magnet there is an invisible region where it can push or pull. We call it the magnetic field.

We cannot see the field, so we draw it with field lines.

Outside the magnet, the lines run from the north pole round to the south pole.

The lines never cross each other.

Where the lines are close together, the field is strong. That is at the poles.

Where the lines are far apart, the field is weak.

A compass needle lines up with the field lines wherever we put it.

Its red end points along the line, towards the south pole of the magnet.

The field pulls on iron and steel, even without touching them.

The pull is strongest at the poles, where the field lines crowd together.

So a magnet has two poles, and a magnetic field all around it, strongest at the poles.

Curriculum

Where this fits

British Columbia, Grade 7

Science, Physics: electromagnetismBC7-SC-22

Previous: What an Electric Current IsNext: A current makes a magnet: the electromagnet

The outcomes and strands follow the British Columbia curriculum.

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