ib physics farady's + lenz's law

faraday's, lenz's law ib definition, rules, sample problems

faraday’s law

The induced EMF for a magnet in a coil is directly proportional to the rate of change of magnetic flux

lenz’s law

This voltage induced due to Faraday's law will oppose the original change that created it.

lenz’s law rules:

when a changing magnetic field ENTERS a wire loop for the first time…

the wire produces a current/magnetic field to OPPOSE

lenz’s law rules:

when a changing magnetic field ALREADY IN a wire loop changes or leaves…

the wire produces a current/mag field that MATCHES

lenz’s law rules:

if the magnetic field is near a wire and is NOT CHANGING…

NO CURRENT is produced, nothing happens

faraday’s law formula (WIRE LOOP)

E = Voltage

A = Area of wire loop (pi*r²)

B = Magnetic field

t = Time

area formula

r = radius

farday’s law formula (single wire)

E = vBl

v = Velocity

B = Magnetic Feild

L = length of wire

right hand rule (WIRE COILS)

• Fingers = Current direction

• Thumb = Magnetic field

• If you wrap your fingers around the coil in the direction of the current, your thumb  points in the direction of the magnetic field

right hand rule (MAGNETS)

• Thumb = North end of Magnet

• Fingers= EMF Direction

• Switches direction if entering wire