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Year 9 - Science

Using electromagets

Magnets and electromagnets

Unit Summary

This unit explores magnetism, including magnetic poles, fields, and Earth's magnetism, along with the principles of electromagnets and DC motors. It focuses on conducting precise scientific enquiries and identifying variables and emphasises accuracy, repeatability, and reproducibility.

Lesson Summary

You will learn to describe how electromagnets are used in cranes, locks, bells and motors.

Key Notes

  • An electromagnetic door lock uses an electromagnet to pull a magnetic bolt to unlock a door.
  • An electric bell often contains an electromagnet that attracts and moves the striker, making it hit the bell.
  • As an electromagnet moves the striker in an electric bell, it breaks its own circuit to let the striker spring back.
  • A motor contains a spinning coil of wire that is an electromagnet.
  • When there is a current in the spinning coil of wire in a motor, other magnets around it will push it round.

Vocabulary To Learn

  • electromagnet: A magnet made by running current through a coil of wire round an iron core.
  • temporary magnet: An electromagnet that loses its magnetism when current stops flowing through it.
  • electric lock: A lock that can be opened with an electromagnet when a switch is closed.
  • electric bell: A bell that uses an electromagnet to strike a clapper on the bell and which resets itself to keep ringing.
  • electric motor: A motor that uses a magnetic field to produce a force.

Common Mistakes To Avoid

  • It is very common for pupils to think that uninsulated wire is needed for the coil of an electromagnet.

3 Quick Questions (With Answers)

1. Explain the scientific idea in this lesson using two key points.

An electromagnetic door lock uses an electromagnet to pull a magnetic bolt to unlock a door. An electric bell often contains an electromagnet that attracts and moves the striker, making it hit the bell.

2. Define this scientific word and use it in context. 'electromagnet'

A magnet made by running current through a coil of wire round an iron core. Include the word in a full scientific explanation, not as a single label.

3. Correct this common scientific misunderstanding.

Mistake: It is very common for pupils to think that uninsulated wire is needed for the coil of an electromagnet. Correction: When discussing an electromagnet, always refer to the insulated wire in its core, which is necessary so the current in each turn adds to the strength of the electromagnet.

More Lessons In This Unit

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