20 de enero de 2015

ELECTROMAGNETISM

ELECTROMAGNETIC INDUCTION

These are videos for helping you to understand the information on pages 137 and 138.

Oersted’s experiment: “All electric currents create magnetic fields”

When the electric current closes, it’s transformed into a magnet and it creates a magnetic field.


Faraday's experiment:  “A changing magnetic field can produce an electric current”

If we move a magnet in front of an electric cable (or inside a coil of wire), it generates electricity in the circuit.


Electromagnetic generators: “Transform mechanical energy (energy from movement) into electricity”

Dynamo:
Consist of a magnet, inside which there is a coil ending in two separate semicircular conductors. Dynamos can generate a direct current.


Alternators:
Consist of a magnet, inside which there is a coil ending in two rings. Alternators generate alternating currents.


Electric motors: “Transform electric energy into movement” “Motors are very similar to dynamos, although they work in the opposite way”

It works on the principles of attraction and repulsion, established by a magnet and a wire through which electric current flows.



Electromagnet: You did it

Transformers: (page 135) “Transformers increase or reduce the alternating voltage”

Transformers consist of two copper coils. If we apply an alternating voltage to one of the coils, it induces a different voltage in the other coil.


IT IS OVER

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