Magnetic fields 2

magnetic flux linkage graph

-just like how magnetic flux will change as the coil rotates magnetic flux linkage changes

-Only difference between the two is that num of coils is constant

-this graph is cosine

Why does a magnet fall slower when its in a tube of copper?

-The magnets field lines are cutting the walls of the tube which is a conductor

-This induces an EMF and a current in the tube

-The current produces its own magnetic field (Right hand rule) which opposes the magnetic field

If an Ammeter was connected what would happen to the current?

-The induced current would rise then fall to 0 and reverse

-This is due to the direction of the magnetic field lines that do flux cutting

Representation at different positions

-In position 1, flux cutting is being done by a field line pointing inwards (inducing EMF and a current one way)

In position 2, the flux cutting is being done equally by field lines pointing in opposite directions, so the currents induced cancel out

-In position 3, the flux cutting is being done by field lines pointing outwards

Current represented on the tube

EMF vs Flux linkage on graphs

ϵmf produced by a rotating coil

ϵ = BANw sin(wt)

ϵmax = BANw

Problem from Flux leakage (inefficieny of transformer)

Solution for flux leakage (inefficieny of transformer)

Problem with eddy current (inefficieny of transformer)

Solution for eddy current (inefficieny of transformer)

Problem for resistance in wires (inefficieny of transformer)

Solution for resistance in wires (inefficieny of transformer)

Problem of heat (inefficieny of transformer)

Solution for heat (inefficieny of transformer)

Primary and secondary current graphs due to Lenz’s law

What information can you on an oscilloscope display?