Electromagnetism Physics 100 Chapt 15 Michael Faraday.
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Transcript of Electromagnetism Physics 100 Chapt 15 Michael Faraday.
Electromagnetism
Physics 100
Chapt 15
Michael Faraday
General circuit
+ -
Appliance+ -
Energy source(device that separates+ & - charge)
I
I
Moving a Conductor in a B-fieldseparates + & - charges
I
Use this to drive an electric circuit
+
+I
+
+
+
Moving wire loop in a B field
+
+
v
An electric current is“induced” in the loop
Either the magnet or the loop can move
+
+
v
an electric current is“induced” in the loop
Magnetic flux () thru a loop
= BA┴
Flux thru a coil of N loops
= N BA┴
Faraday’s law
change in N BA┴
elapsed time
Induced voltage in a circuit =change in elapsed time
EMF =
“Electro-Motive Force”
Michael Faraday
Rotating coil in B field
A┴ = 0 =0
B
Rotating coil in B field
A┴ = Acoil = maximum
B
Rotating coil in B field
A┴ = 0 (again) = 0
B
AC voltage
Lenz’ Law
v v
B B
+ +
N
S
the fall producesan induced current
the B-field producedby the induced currenttries to impede the fall
B-field from induced current
B-field from induced current
I
Lenz’ law
An induced voltage always gives rise to an electric current that creates a magnetic field that opposes the influence that produced it.
Maglev trains
Maglev