2. Remember this: (from 12.1 Electromagnetic Induction)As a
conductor moves through a magnetic field...... The current that
flows makes Flemings Left-Hand its own force on theRule force
created bythe Current conductor. You can use Flemings Left Hand
Rule to predict it too. This force is in the opposite direction to
the motion thatForce creating is creating the current!the Motion If
there wasnt an opposing Force being made then once you started
pushing the Conductor through the field it would carry on making
current for ever with no more force needed.This would contradict
the Law of Conservation of Energy 3. Lenzs Law This just says that
the direction of the Induced Current is such that it opposes the
change that causes it.If you push a wire through a field the
induced current makes aforce that pushes backIf a field is pointing
one way and a conductor moves throughit, then the induced current
makes a field that points theopposite way 4. Faradays and Lenzs
Laws Example 1A) Faradays LawAs the magnet approaches the coil theB
field increases and the changingflux enclosed by the coil Induces
anemf in the coil that causes current toflow.The size of the emf is
equal to therate of change of the flux enclosedby the coil. 5.
Faradays and Lenzs Laws Example 1B) Lenzs LawThe direction of the
Inducedcurrent is such that it opposes thechange producing it (the
magnetmoving towards the coil)The current in the coil has to makea
magnetic field that pushes theMagnet away....The Right hand grip
rule showshow the current must flow. 6. Faradays and Lenzs Laws
Example 2A) Faradays LawWhen the current in circuit A flows, a
magnetic field is created which causesthe magnetic flux enclosed by
the coil in Circuit B to increase.This increasing flux induces a
current in coil B. It only happens for a milli-second when it is
switched on.After that the flux is constant so there is no induced
current. 7. Faradays and Lenzs Laws Example 2B) Lenzs LawThe
direction of the current in B must oppose the change producing it
(theincreasing field from A).To do this the current induced in B
flows to create a Magnetic field in theopposite direction to that
from Athis is how a transformer works 8. Magnet in Copper
PipeFaradays LawAs the magnet falls throughthe copper pipe there is
achanging Flux on thecopper. This induces eddycurrents in the
copper pipe. http://www.youtube.com/watch?feature=player_
embedded&v=dnK6oxbPSM4Lenzs LawThe eddy currents flow insuch a
way that they createa magnetic field whichopposes the change
thatproduced them. http://www.youtube.com/watch?v=otu-KV3iH_I 9.
Induction Braking Eddy current brakingFaradays LawAs the magnet is
brought near tothe rotating disc there is achanging Flux on any
point inthe copper. This induces eddycurrents in the copper
disc.Lenzs LawThe eddy currents flow in sucha
http://www.youtube.com/watch?v=SK0EdikjC24&featurway that they
create a magnetic e=relatedfield which opposes the changethat
produced them.The Railway
Gazettehttp://www.railwaygazette.com/news/single-view/view/eddy-current-braking-a-long-road-to-success.htmlhttp://demonstrations.wolfram.com/MagneticBraking/You
might need the Wolfram plugin for this to work 10. Induction
Braking Eddy current brakingFoucaults Disc a
simulationhttp://www.magnet.fsu.edu/education/tutorials/java/foucaultdisk/index.html
11. Quantum Levitation & Flux PinningSuperconducting DiscThe
upper disc is asuperconductor in which anInduced Current is created
bythe changing flux as it isbrought near to the lowermagnet. This
induced currentflows constantly because thesuperconductor has
zeroresistancehttp://www.youtube.com/watch?v=Ws6AAhTw7RALenzs
LawThe induced currents flow inExplanationsuch a way that they
create amagnetic field which opposesthe change that producedthem.
http://www.divshare.com/download/17914105-09cFlux Pinning
http://en.wikipedia.org/wiki/Flux_pinning
