11TH GRADE · MAGNETISM
Magnetic flux and induction
Flux, electromagnetic induction, self-induction and field energy.
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Basic Concepts
Electromagnetic induction
The occurrence of EMF in a circuit when the magnetic flux through it changes.
EMF is created precisely by a change in magnetic flux; the resulting current, according to Lenz's rule, counteracts this change.
Self-induction
The occurrence of EMF in a circuit when its own current and magnetic flux change.
The coil prevents a rapid change in its own current: the greater the inductance and the rate of change of current, the greater the EMF.
Physical quantities
Magnetic flux
A measure of the magnetic field passing through a surface.
Unit: weber ·
induced emf
EMF that occurs when magnetic flux changes.
Unit: volt ·
Number of turns
The number of turns of conductor in a coil.
Unit: dimensionless quantity
Magnetic flux change
The difference between the final and initial magnetic fluxes.
Unit: weber ·
Inductance
The ability of a circuit to create its own magnetic flux when current passes.
Unit: Henry ·
Current change
The difference between the final and initial currents.
Unit: ampere ·
Self-induced emf
EMF arising due to changes in current in the circuit itself.
Unit: volt ·
Magnetic field energy
The energy stored in the magnetic field of the coil.
Unit: joule ·
Lesson formulas
Magnetic flux
Magnetic flux depends on the induction, area and orientation of the surface.
Weber's definition
One weber is equal to a volt-second and a tesla-square meter.
Law of Electromagnetic Induction
The module of the induced emf is equal to the rate of change of the total magnetic flux.
Self-induced emf
The self-inductive emf is proportional to the inductance and the rate of change of current.
Coil magnetic field energy
The energy of the magnetic field depends on the inductance and the square of the current.
EMF of conductor movement
EMF occurs when a conductor moves in a magnetic field.
Maximum EMF of the rotating frame
The amplitude of the EMF of the frame is proportional to the number of turns, induction, area and angular velocity.
Flux linkage and current
The self-magnetic flux is proportional to the inductance and current.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.