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Year 9

Electromagnets

I can describe how to make a magnet using an electric current.

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New
New
Year 9

Electromagnets

I can describe how to make a magnet using an electric current.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. When there is an electric current in a wire, there is a magnetic field around the wire.
  2. When there is an electric current in a coil of wire, the magnetic field around each loop adds to make a stronger field.
  3. An electromagnet is made by wrapping a coil of wire around a core.
  4. An electromagnet is a magnet that can be turned on with an electric current, and turned off.

Common misconception

A magnetic field is the same as the electric field around a charged object.

Demonstrate that a balloon with a static electric charge does not affect the magnet in a plotting compass.

Keywords

  • Magnetic field - this exerts a force on magnets and magnetic materials

  • Coil - a wire wound round in loops and looks like a spring

  • Core - the centre of an electromagnet around which a wire is wound to make a coil

  • Turn - a single loop of wire in a coil

  • Electromagnet - a magnet made using a coil, a core and a power supply

Use single core insulated wire to make the electromagnets. Each time extra turns are added to the coil, push the coil to the head end of the nail and twist the ends together to keep the coil compact. (N.B. more turns on one coil and not more coils.)
Teacher tip

Equipment

Single core insulated wire, soft iron core, power supply, crocodile clips, paperclips, plotting compass.

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.
Which of the following metals are magnetic?
Correct answer: iron
sodium
Correct answer: cobalt
copper
Q2.
Which statement about the magnetic field lines round a bar magnet is correct?
They point out of both the N–pole and the S–pole.
They point into both the N–pole and the S–pole.
Correct answer: They point out of the N–pole and into the S–pole.
They point out of the S–pole and into the N–pole.
Q3.
Earth's magnetic field behaves as if there is a magnet inside the planet. Which of the following statements about this imaginary magnet is correct?
Correct answer: The S–pole of the magnet is at Earth's North Pole.
The S–pole of the magnet is at Earth's South Pole.
The S–pole of the magnet is at Earth's equator.
The N–pole of the magnet is at Earth's equator.
Q4.
Where is Earth's magnetic field strongest?
at the equator
Correct answer: at the north and south poles
at the Bermuda triangle
on top of the highest mountain
Q5.
Which of the following will not deflect a magnetic compass needle?
an iron nail
a steel fork
a nickel coin
Correct answer: an electrostatically charged balloon
Q6.
Which of the following statements about the poles of magnets is correct?
A north pole will attract a north pole.
Correct answer: A north pole will attract a south pole.
A north pole will repel a south pole.
A south pole will attract a south pole.

Exit quiz

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6 Questions

Q1.
Which of the following would not cause a compass needle to deflect?
Correct answer: an electrostatically charged plastic ruler
a copper wire carrying current
Earth's magnetic field
an iron rod
Q2.
Which of the following is not needed to make a strong electromagnet?
an iron rod
insulated wire
a power supply
Correct answer: paperclips
Q3.
Why do paper clips fall off the electromagnet when the current is turned off?
An image in a quiz
The magnetism has returned to the power pack.
Correct answer: There is no current in the coil.
The wire has overheated.
The paperclips repel the core.
Q4.
Which of the following changes will not make an electromagnet stronger?
An image in a quiz
Increasing the current in the wire.
Increasing the voltage across the wire.
Increasing the number of turns in the coil.
Correct answer: Increasing the number of paperclips.
Q5.
Which of the following will increase the strength of the magnetic field in a coil of insulated wire?
Increasing the diameter of the coil.
Increasing the resistance of the wire in the coil.
Correct answer: Putting an iron core in the coil.
Putting a copper core in the coil.
Q6.
What is the shape of the magnetic field lines caused by a straight, current–carrying wire?
spherical around the wire
straight and away from the wire
Correct answer: circular around the wire
straight and in the same direction as the wire

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