Survey

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

History of electrochemistry wikipedia, lookup

Electromagnetic compatibility wikipedia, lookup

Ohm's law wikipedia, lookup

Electrostatics wikipedia, lookup

Neutron magnetic moment wikipedia, lookup

Superconducting magnet wikipedia, lookup

Magnetic nanoparticles wikipedia, lookup

History of electromagnetic theory wikipedia, lookup

Aurora wikipedia, lookup

Friction-plate electromagnetic couplings wikipedia, lookup

Induction heater wikipedia, lookup

Magnetic field wikipedia, lookup

Hall effect wikipedia, lookup

Electricity wikipedia, lookup

Magnetic monopole wikipedia, lookup

Computational electromagnetics wikipedia, lookup

Electric machine wikipedia, lookup

Earth's magnetic field wikipedia, lookup

Magnet wikipedia, lookup

Maxwell's equations wikipedia, lookup

Coilgun wikipedia, lookup

Magnetic core wikipedia, lookup

Force between magnets wikipedia, lookup

Multiferroics wikipedia, lookup

Magnetism wikipedia, lookup

Ferrofluid wikipedia, lookup

Magnetoreception wikipedia, lookup

Superconductivity wikipedia, lookup

Scanning SQUID microscope wikipedia, lookup

Magnetochemistry wikipedia, lookup

Electromotive force wikipedia, lookup

History of geomagnetism wikipedia, lookup

Magnetohydrodynamics wikipedia, lookup

Lorentz force wikipedia, lookup

Eddy current wikipedia, lookup

Electromagnetic field wikipedia, lookup

Electromagnetism wikipedia, lookup

Transcript
```10. Electromagnetic Induction
If a magnetic field changes in time there is an
induced electric field.
In differential form, the field equation is
B
E  
t
In integral form,
d
CE  d l   dt
where  is the magnetic flux through any surface
with boundary curve C.
(Why are the two equations equivalent?)
G L Pollack and D R Stump
Electromagnetism
1
Lenz’s law
The direction of the induced electric field in
electromagnetic induction opposes the change of
magnetic flux; i.e., if a conductor is present then the
induced current produces a magnetic field in the direction
tending to maintain the flux.
Self-inductance
A current I in a conducting loop creates a magnetic field.
The flux through the loop is proportional to the current,
 = LI . The constant of proportionality L is the selfinductance, which depends on the geometry of the loop.
If I changes in time there is an induced emf around the
loop, which is by Faraday’s law   L dI dt
.
G L Pollack and D R Stump
Electromagnetism
2
Exercises
• Show that an LC circuit is an oscillator.
• Show that the energy in an inductor is
U  12 LI 2 .
• Show that the energy density of the magnetic field is
umag  B 2 20 .
G L Pollack and D R Stump
Electromagnetism
3
```
Related documents