Université Kasdi Merbah Ouargla
3ème année LMD : Contrôle et Automatique, télécommunication
Module : Anglais
FARADAY’S LAW OF ELECTROMAGNETIC INDUCTION
In 1831, where pursuing his experiment, Joseph faraday made
one of the most important discoveries in electromagnetism, know is
known as faraday’s law of electromagnetic induction, It revealed a
fundamental relationship between the voltage and flux in a circuit.
Faraday’s law states that:
1-If the flux linking a loop (or turn) varies as function of time; a
voltage is induced between its terminals.
2-The value of the induced voltage is proportional to the rate of
change of flux.
By definition, and according to the system of units, when the flux
inside a loop varies at rate of 1 Weber per second, a voltage of 1V is
induced between its terminals, consequently, if a flux varies inside a coil
of N turns, the voltage induced is given by: faraday’s law of
electromagnetic induction opens the door to a host of practical
applications and establishes the basis of operation of transformers,
generators and alternating current motors.
In many motors and generators, the coils move with respect to
a constant flux.
The relative motion produces a change in the flux linking the coils and
consequently, a voltage is induced, according to faraday’s 1aw.
However, in this special case, it is easier to calculate the induced
voltage with reference to a conductor, rather than with reference the coil
itself. In effect, whenever a conductor “cuts” a magnetic field voltage is
induced across its terminals. The value the induced voltage is given by:
VOLTAGE INDUCED IN A RECTANGULAR CONDUCTOR
Following the discovery of Faraday’s law of electromagnetic
induction’ scientists and technicians of the 19th century did not wait long
to invent and build all kinds of mechanical machines to generate
electricity. The operating principal of these machines is always based
upon the relative motion of a rectangular coil with respect to a
magnetic. Consider a permanent magnet SN revolving at constant
speed inside a stationary iron ring. The ring reduces the reluctance of
the magnetic circuit; consequently, the flux density in the air gap is
greater than if the ring were absent. A rectangular conductor ABCD is
mounted inside the ring, but insulated from it.
Année universitaire 2014/2015