Laplace forces - Induction

Magnetostatics and Laplace forces

Magnetic field created by a coil and an infinite solenoid
Magnetic moment of a coil:

Know the torque exerted by an external field on a coil


Action of a magnetic field on a current-carrying conductor - Laplace forces:

Establish the expression of the resultant of the Laplace forces in the case of a conducting bar placed in a stationary magnetic field.
establish the expression of the torque moment of Laplace's mechanical actions in the case of a current-carrying coil placed in a stationary, uniform external magnetic field


Potential vector


Electromagnetic induction

Magnetic ARQS:

Rewrite Maxwell's equations in magnetic ARQS


Induced current :

Predict the direction of induced current according to the direction of magnetic flux variation.




Fixed circuit in a time-dependent magnetic field

Neumann's induction:

Use Lenz's law
Use Faraday's law to calculate induced fem
Use electromotive field to calculate induced fem
Use local or integral Ohm's law to calculate current


Self-induction, self-flux and self-inductance :

evaluate the self-inductance of an infinite coil (the magnetic field created by the coil will be given)
Conduct an energy balance in a system where self-induction occurs, based on an equivalent electrical diagram


Interacting coils : Mutual inductance between two coils
Magnetic energy:
Transformer application:

Establish the transformation ratio of an ideal transformer




Moving circuit in a stationary magnetic field

Lorentz induction:

Use Lenz's law
Use Faraday's law to calculate an induced fem.
Use the electromotive field to calculate an induced fem
Use local or integral Ohm's law to calculate an intensity


Conversion of mechanical power into electrical power:

Laplace rail, electromagnetic braking
Carry out an energy balance in a self-induction system based on an equivalent electrical diagram


Rotating circuit in a uniform magnetic field:

Generator


Conversion of electrical power into mechanical power:

DC motor with plane air gap, electrodynamic loudspeaker




Magnetic media and transformer

Maxwell's equations in a magnetic medium and in the ARQS:

Magnetizing currents
Use the magnetic excitation vector H and rewrite the Maxwell-Ampère equation in a magnetic medium


Integrated (global) form of Maxwell's equations:

Faraday's Law, Ampère's Theorem


Magnetic environment: hysteresis cycle
Application to real transformers:

Constitution
Voltage transformation
Current transformation
Power transformation
Current normalization (homologous terminals)
Iron and copper losses, energy

Magnetostatics and Laplace forces
Electromagnetic induction
Fixed circuit in a time-dependent magnetic field
Moving circuit in a stationary magnetic field