Download Induced EMF

Induced EMF
electricity and _________
magnetism
So far we've dealt with _________
as separate topics. From now on we'll investigate
the inter-connection between the two, starting with
induced ______
the concept of _________
emf . This involves
voltage by changing the
generating a _________
field that passes through a ______
coil
magnetic ______
_________
of wire.
Magnetic Flux
magnetic _____
flux is a measure of the number
The _________
field _____
lines passing through an
of magnetic ______
loop of wire with an area A is in a
area. If a _____
magnetic field B, the magnetic flux is given by:
_________
Where:
Φ = BA
B = magnetic field strength (Tesla)
A = Area of loop (m2)
Φ = magnetic flux (Weber - Wb)
1 Weber = 1 Tm2
emf will be induced. There are
If the ____
flux changes, an ____
three ways an emf can be induced in a loop:
therefore _____
1. Change the magnetic field
2. Change the area of the loop
3. Change the angle between the field and the loop
Faraday’s Law of Induction
emf can be induced in a
As we have learned, an ____
magnetic _____
flux through the coil is
coil if the _________
changed It also makes a difference how ____
fast the
________.
more emf
change is; a quick change induces ______
than a gradual change. This is summarized in
Faraday’s
Law __
of _________.
Induction The ________
induced
___________
_____
loops
emf in a coil of N _______
produced by a change in
flux in a certain time interval is given by:
Φ
ε=N t
or
(BA)
ε=N t
Lenz’s Law
current that sets
induced emf generates a _________
The _________
field which acts to __________
OPPOSE
magnetic ______
up a __________
the change in magnetic flux.
I know – by now you’re saying to yourself
WHAT THE FLUX THIS GUY
TALKING ABOUT!!!!!!!!!!!!!!
Let’s do some examples to explain.
X
Determine the
direction of induced X
current in the
X
following scenarios
X
(a) The loop sits still
(b) The loop is pulled
down
(c) The loop is pushed up
(d) The loop is pushed
right
(e) The loop is pulled left
(f) The loop is rotated
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
B
(a) No current induced
(b) clockwise
(c) counterclockwise
(d) No current induced
until it begins to leave the field in
which case it would be clockwise
(e) clockwise
(f) clockwise
until it passes vertical, then it
becomes counterclockwise