Download Chapter 34

Reading #13
“Electromagnetic Induction”
1.
Look at the diagrams on page 306, remember that they are using a grid of X’s
to show a magnetic field which is perpendicular to the page and pointing into
the page. Using the right hand rule, your thumb would be pointed down.
The conducting wire is moving to the right with a velocity of “v”. Using the
right hand rule, your pointer finger is extended to the right.
To conclude the direction of the force of the magnetic field and hence the
electric field, extend your middle finger, which way does it point??
Hopefully back at you!!
2.
As a result of the wire in the magnetic field, the electrons are forced in the
same direction as the FB. A charge in the wire feels two
forces:________________ and _____________________.
If q is positive then _____________________________________________.
If q is negative then ____________________________________________.
3.
Equilibrium in the wire will occur when _____________________________.
4.
The presence of the electric field creates a _________________ between the
ends of the rod. The end of the rod with the negative charge has a potential
_________ than that of the positive end.
5.
Potential difference in volts (V=El) because E=vB then V=vbL.
6.
Explain “motional emf” in your own words:
7.
As the motional emf is induced, the current will flow in the opposite direction
of the electric field creating power.
P=IV =Iε = IvBl
The energy provided by the external agent is transformed first into
__________ and then into ____________.
8.
Electromotive force can also be induced by magnetic flux. The formula for
magnetic flux is _________________________. If the magnetic field varies
through the area than you must change the formula to ______________.
9.
Complete #4 from page 1076 from our book here:
10.
The concept of magnetic flux is __________because a change in magnetic
flux can induce a potential difference or _______________. According to
Faraday’s Law, the magnitude of the ___________ in the circuit is equal to
the rate of change of the magnetic flux through the circuit over time.
Є avg =
11.
OR
Є=
According to Lenz’s Law, the induced emf can produce ________________.
Look at page 1053 in our book and finish the chart below:
B up and
steady
B up and
increasing
No change in
flux
UP change in
flux
No induced
field
DOWN
induced field
No induced
current
Induced
current
12.
Use your chart to answer # 7 from page 1077 here:
13.
Complete #11 from page 1077 here:
No current
flow
CW Current
flow
14.
Look at example 13.4 in handout and complete the following:
a) A bar magnet has ________ poles. The magnetic field _________ the
north pole and _______the south pole.
b) As a bar magnet is dropped through a loop of wire NP first, the direction
of the induced field will be _______ and the current induced will
flow_________.
c) As the bar magnet is dropped through the loop SP first, the direction of the
induced field will be _______ and the current induced will
flow_________.
Both b and c should follow the right hand rule!!! B up, current flows ccw
therefore fingers curl ccw as well!!!
15.
Look at example 13.5, notice how it brings together solenoid and flux.
Summarize the “flow of thought/explanation” connecting Є and current in a
solenoid:
16.
Complete #60-61 from page 1081 here:
17.
What happens when a loop is placed around the central axis of a solenoid? As
the current in the solenoid is increased, he strength of its magnetic field
_______. This changes the _______ through the wire and therefore the
______. Looking at the diagram on page 318 of the handout, if B inside of the
solenoid is orientated __________ than the current will flow _________. The
force that pushes the charges around the wire is ______ with E the being
induced electric field.
18.
What is the symbol for inductor in a schematic?
19.
Explain in your own words how an inductor in a circuit creates self-induced
emf and back emf:
20.
The energy stored in the inductor with a circuit can be calculated through the
formula U=1/2LI2
21.
Look at example 13.10 and complete #78 from page 1081 in our book:
22.
An LC circuit contains both ___________ and __________. The presence of
an inductor in the LC circuit prevents the capacitor from ________________.
What is unique about the way energy flows between the capacitor and the
inductor?
This energy flow causes the circuit to oscillate creating an angular frequency
through the equation …
OR
23.
The charge available during this oscillation will vary according to the amount
of time the switch has been closed through the equation …
24.
Complete #22 , 23,76 from pages 1078-1081 here: