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.
• 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
• 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.
• 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 combined magnetic fields are much
stronger than the magnetic field of one or the
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
Where are they used?