"Electricity is actually made up of extremely tiny particles
called electrons, that you cannot see with the naked eye
unless you have been drinking."
"You do not really understand something unless you
can explain it to y
Current and Direct
Resistance and Ohms Law
A Structural Model for Electrical Conduction
Electric Energy and Power
Sources of emf
As with any vectors, magnetic field vectors can be
added together by superposition
You have to take both magnitude and direction into
The vectors could
get ugly, but just
recall RHR2 and
vector rules of
An electron travels at 2.0x107m/s in a plane
perpendicular to a 0.10T large uniform magnetic field
directed into the screen as shown below. Describe
its resulting path (both magnitude and direction).
X Xv X
History of Magnets
Magnets were discovered by early man.
Asia Minor has region known as Magnesia where
rocks would attract each other.
Early researchers found that if you put a magnet on
a string it would want to face a certain dire
Lets say we have a circuit with two resistors in
When these two resistors are hooked up to the
battery, a current is established.
In this circuit, both
resistors would have the
same potential difference
as the bat
Recall from mechanics that power was a measure of
the work done in a given amount of time:
The SI unit of power is still the Watt (Joule/sec).
Although you should also be aware of kW and horsepower.
Work is equal to the change
Up until now, we have dealt with electrostatics (i.e.
charges that do not move).
We now define electric current, I, to be the rate at
which electric charge passes through a surface or
The SI unit for current is the A
Electrical potential: superposition
Electrical potential due to a single point (or spherical)
charge, assuming that the potential at infinity is zero
V = ke
What is the potential due to two (or a set of N) of
An equipotential surface is a surface on which all points
are the same potential.
Normally, the potential differences between nearby
equipotential lines are the same, say 1V, 1kV
It takes no work to move a particle al
rong statement from a
onceptuoal question in quiz 1:
he electric flux through a
urface is proportional to the
osine of the angle between the
lectric field and the surface.
E = E A = EA cos
In reality, the el
We will skip Electric field due to continuous charge distributions.
Flux is the amount of something that flows through a
Electric flux, E, measures the amount of electric field
lines that pass through a giv
The direction of force in the
Coulombs Law is determined by the
sign of the two charges involved.
If you have unlike charges then
the force will be attractive along
the line connecting the two
If you have like