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natural
Hans Christian Oersted
He discovered that electric
current produces a magnetic
force.
He couldn’t explain the
phenomenon.
Two other scientists
investigated further…
André-Marie Ampere
He decided to study the relationship between
electricity and magnetism.
He discovered the electron
(he called it the
‘electrodynamic molecule’).
Michael Faraday
He showed that by moving a loop of wire over a
magnet, an electric current is produced in the
wire.
A changing magnetic field
produces an electric field.
He called this the
‘electromagnetic rotary device’
Dynamo (electric motor)
Bar magnet
Permanent magnets: they always have a
magnetic field.
They have TWO POLES: NORTH & SOUTH.
They attract some metals: iron, steel…
They attract or repel other magnets.
Magnets attract and repel
Like poles repel…
…unlike poles attract.
The Earth’s magnetic field
Magnetosphere – from the South Pole to the
North Pole.
North Pole of the Earth = south pole of the
magnetosphere
The effects of electricity
Thermal energy
The amount of thermal energy depends on the substance.
As electric current travels through
a copper wire, very little thermal
energy is produced.
However, in an oven, electric
current passes through a substance
that produces a lot of thermal energy.
The effects of electricity
Chemical reactions
Electrolysis is a chemical reaction that is produced when an
electric current flows through a liquid solution of charged
particles.
The positively charged atoms in the solution are attracted to the
negative electrode. They gain electrons.
Negatively charged atoms are attracted to the positive electrode.
They lose electrons.
The solution is transformed into two separate substances.
Uses of electromagnets
Electric bell
1. The switch is closed and electric current
flows through the circuit.
2. The current produces a magnetic field in
the electromagnet.
3. The hammer is attracted to the
electromagnet and hits the bell.
4. The movement of the hammer breaks the
circuit, and the hammer returns to its
original position. Then the cycle begins
again.
Uses of electromagnets
Maglev – magnetic levitation train
1. The Maglev has magnets in the base of the train.
2. The tracks have magnets at either side.
3. The lower magnets are positioned so that they will repel the
magnets in the train, causing the train to levitate above the
track.
4. The magnets above and in front
of the train attract the magnets
in the train, causing the train to
move forward.