Electromagnetism

Hans Christian Oersted

• Discovered the relationship between electricity and magnetism in 1820.

• Held a compass near a wire carrying an electric current. When compass was close to the wire, the compass needle no longer pointed north.

• He concluded that an electric current produces a magnetic field.

Electromagnetism

• The magnetic field from a wire is not strong enough to be useful. In order to be useful, it needs to things – a Solenoid and an electromagnet

Solenoid

• A coil of wire that produces a magnetic field when carrying an electric current.

• The magnetic field of each loop combines to strengthen the magnetic field.

Electromagnet

• A iron core inside a solenoid – the magnetic field of the electromagnet is the magnetic field of the iron core + the magnetic field of the solenoid.

• The combined magnetic fields are much stronger than the magnetic field of one or the other individually

Useful…

Electromagnets are very useful and easy to use because they can be turned on and off. The magnetic field only exists when electricity is running through the wire making up the solenoid.

Where are they used?

• Doorbells• Speakers• Cars• Computers• Stoves (induction)• Maglev trains

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