2nd year of post-compulsory secondary education
Magnetic field
José Luis San Emeterio
 Magn.  
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Self-induction
   A very simple way of producing induced currents in a circuit is to change the intensity of the current that flows through it, as this generates a variable magnetic field. This phenomenon takes place when you switch on an electric device.

   The phenomenon is much stronger if there is a coil in the circuit, as in the figure on the left.

   You can study the phenomenon of self-induction of a coil in the following visual  , where you will be able to see how it depends on some of the properties of the circuit, as the law of Henry states:

emf is the self-induced electromotive force, dI/dt is the variation of the intensity of current with time and L is the self-inductance or inductance of the coil, which is a property of the coil and is measured in henries. Its value is equal to:

ley de Faraday Lenz

where μ is the magnetic permeability of the medium, n is the number of loops and l is the lenght of the coil.

Background information
Natural magnets
Lines of force
Magnets and currents
Conclusions
The effects of the magnetic field
on a charged particle
on a straight cable
on a loop
Conclusions
The creation of magnetic fields
by a charged particle
by a rectilinear current
by a coil
An explanation of natural magnetism
Conclusions
Induced currents
Magnetic flux
The laws of Faraday and Lenz
Self-induction
Conclusions
Alternating current
The generation of alternating currents
A circuit of alternating current
Conclusions
Evaluation