Editing and Proofreading
One lesson I learned to late
One lesson I learned too late was hiding peoples items. I used to hide peoples items for fun to witness
their reaction. One time, that went over the top is when my friend and I hid another friends comp
The Electric Dipole
Find the electric field at P
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Maxwells Electrodynamics
Electromagnetism as Maxwell found it
E dA q
enclosed
/ 0
S
B dA 0
S
d
E ds d t B d A
C
S
B ds J d A
0
C
S
Magnetic field on the perpendicular bisector of a thin straight
wire of length L carrying current I.
Compute B usinf the
Some important results from
chapter 24
Suppose we are handed a spherical but not necessarily
uniform distribution of electric charge on an insulating
ball. Is there a way to figure out what the distribution is
solely by performing experiments outside the
RC Circuits
Initially uncharged capacitor. Throw switch to a.
Capacitor begins to charge. Positive charge accumulates
on the upper plate, negative charge on the lower plate.
Capacitor begins to charge. Positive charge accumulates
on the upper plate, negat
More on Electric Charge
charge polarization of conductors
charge polarization of insulators
The atoms of most materials have a
regular arrangement.
Quantization of electric charge
Quantization of electric charge
Cannot continue the process indefinitely
Qu
Magnetic Forces and Torques on
Currents
What will be the direction of the force on the wire if
current flows up the page?
Let a current flow in a wire and consider a small piece of wire
of length ds. Define a vector d s whose magnitude is the length of
th
Induced Electric Fields
Whenever the surface enclosed by a conducting loop experiences a
changing magnetic flux, there is always an emf around the loop associated
with this changing flux.
B B dA
S
E
d B
dt
E N
d B
dt
Faraday's law for a single turn of wi
Inductance
An inductor is an arrangement of wires or other conductors used to
produce a magnetic field.
Circuit theory symbol:
Consider an inductor composed of N turns of wire.
When a current I flows through the inductor, a magnetic field B I
is produced.
Induction motor
Direction of torque on rotating magnet?
Conservation of angular momentum
A
C
Four solenoids, shown at
time t 0, driven by
ac currents at the same
frequency but with 90
phase differences.
B
D
A
Four solenoids, shown at
time t
C
1
4
B
T , d
The Flux Concept
Total current through the disk
J dA
disk
Total current through the hemisphere
hemisphere
J dA
For a closed surface, the convention is to choose
the areal vector outwards, away from the enclosed
volume.
You can define the flux of any ot
The Electric Field
9 10 Nm
9
F3
33.75 N
i
2
2 10 C 3 10 C
i
4 10 m
/C
6
2
2
2
6
F6 2F3 67.5 N
i
F1 1 F3 11.25 N 11.25 N
i
i
3
In all these cases, the force on a point charge
is proportional to the charge. For charges
placed at P, F / q in indep
Good Idea Gone Bad
It was a warm summer Mediterranean evening on the island of Mykonos. My Parents and I had hired
two chefs and a waiter to make a dinner for us and our friends. We had done this for them to thank
them for buy us dinner a couple of nights
The Good and Bad about scuba diving
Scuba Diving is a world Renown Activity too do. It requires both patience, practice and skill in order to
dive. There are many risks involved with doing this activity, depending on your wellbeing and your
attitude. As w
The Good and Bad about scuba diving Revised
Scuba Diving is a world Renown Activity too do. It requires both patience, practice and skill in order to
dive. There are many risks involved with doing this activity, depending on your wellbeing and your
attitu
The Good and Bad about scuba diving
Scuba Diving is a world Renoun Activity too do. It Requires both pacience, practice and skill in order to
dive. There are also many risks involved with doing this activity. As well as many great parts to diving
includin
Describe the prewriting strategy that you used for this lesson and explain how well it
worked.
For This lesson we used the Lists of Lists way of gathering ideas in order to come up with a brain storm.
We are using this way in order to come up with a more
Applications of Capacitors
V E
q C V
0 A V
d
V E
q C V
0 A V
d
Suppose d is decreased. Then q is increased:
there will be a flow of charge through the circuit.
This flow of charge is an electric current and it
can be made to do useful work.
V E
q C V
Think of the electric current as due to the motion of small
particles, called charge carriers. The average particle has
charge q and the particles are distributed uniformly
throughout the conducting volume.
Think of the electric current as due to the moti
Sources of the Magnetic Field
A magnetic north pole, placed in an external
magnetic field, is attracted in the direction of
that field.
A magnetic south pole, placed in an external
magnetic field, is attracted in the opposite
direction of that field.
What
The Hall Effect
Can we use magnetic fields to tell us what is the
sign of the charge carriers in ordinary conductors?
Suppose the charge carriers are positively charged
FB q v B
Suppose the charge carriers are positively charged
FB q v B
Suppose the charg
Inductance problems
The switch in the above circuit is closed and kept closed for a long time. Eventually,
the emf across the inductors becomes zero. The switch is then opened
A. After the switch is opened, find the maximum charge on the capacitor.
B. Aft
General DC Circuits
series connections of resistors: Req R j
j
parallel connections of resistors: 1/Req 1/ R j
j
Simplifying a simple circuit
I bat
3V
0.169A
17.769
In particular, the current through
the 2.769 Ohm resistor is 0.169 A.
The current throug
Charged conducting spheres
Consider two neutral metal spheres, one
of them of large radius R1 and the other
of smaller radius R2 and imagine that
they are separated by a distance that is
much greater than their radii.
We place a charge Q on the large
sphe
Computing Induced Currents
Whenever the surface enclosed by a conducting loop experiences a
changing magnetic flux, there is always an emf around the loop associated
with this changing flux.
B B dA
S
E
d B
dt
E N
d B
dt
Faraday's law for a single turn of
Dielectrics
Electrical properties of insulators
The atoms of most materials have
a regular arrangement.
When an electric field is imposed
on the dielectric, the atoms
polarize
The polarization tends to cancel
out internally
There is, however, an unbalance
Chapter 29 problems
The three figures above show currents in uniform magnetic fields.
All currents are the same, their lengths are the same and all
magnetic fields have the same magnitude.
Which current experiences the strongest magnetic force?
A. 1
B. 2
Combinations of Capacitors
q1 q2 0
q1 q2
q2 q3 0
q2 q3
When capacitors are connected in series,
the charge is the same on all the capacitors
q1 q2 q3
How much charge passed through the battery?
A. q
B. 2q
C. 3q
D. none of these
qbat q
How much charge pass
Applications of Amperes Law
Current flows uniformly over a wire of radius R carrying a total
current I. Find the magnetic field everywhere, inside and
outside the wire.
First part of problem: r < R
What do the magnetic field lines
look like inside the wir