Faradays law of induction

• A changing magnetic field will induce an EMF in a loop of wire

• EMF- electromotive force => elektromagnetisk induktion

  => Which Is what causes electrons to move and form a current

• changing the area of the loop of wire induces a current, too, and so did changing the angle between the loop and the magnetic field.

Magnetic flux- magnetisk flödestäthet

=> a measure of the magnetic field running through a loop go wire.

=> when the field changes it induces an EMF

BxAxcos0= 0b=> magnetic flux

alternative: BxA=0b

• if the magnetic flux through a loop of wire decreases over time, the EMF increases accordingly.

• if the magnetic flux increases over time, the EMF decreases

  EMF= -number of loops x change in flux/ change in time

• Faradays law of induction lets us calculate how much EMF and therefore, how much current will be induced in a loop of wire by a change in magnetic flux.

  Lenzs law

  => says that the magnetic field generated by the induced current will be in the direction opposite the change in magnetic flux.

  Eddy current- virvelströmmar

• Lenzs law

  alternators and dynamos

• Direct current - alternate current

  => electrons flow in only one direction => electrons change their directions

• an alternator uses magnetic fields to create alternating currents. two commutators

• a dynamo uses magnetic fields to create a direct current. one split commutator

• Change the size of the magnetic field then the size of the current increases

  => also happens if we increase => the number of turns

  => the area of the coil

• changing the rotation speed leads to increase in both size and frequency of the current.

  Transformers

• consists of two or more coils of wire wrapped around the same magnetic field.

• If a DC current passes through then the transformer behaves the same way as if they were replaced with normal wires

• if an AC current passes through one coil causes current to also flow in the other coil.

• Depending on how many turns are in each coil, the transformers can mak the voltage bigger or smaller

  => more turns=> higher voltage→more energy per particle

  =>less turns=> lower voltage→ less energy per particle

• the transformers does not create or destroy energy it only moves the particles from one side to another

• the number of charged particles flowing each second is what we refer to as the current

• lower voltage <=> higher current

• Higher voltage <=> lower current