Transcript Slide 1

Physics Final 2008
Chapters 17, 18,19, 20, 21,
12, 13, 14, 15
Electrostatics
Charges can be positive or negative
A proton has a positive charge at 1.6 x 10-19 C
An electron has a negative charge at -1.6 x 10-19 C
Electrons can move, protons are stuck
Opposite charges attract
Coulomb’s Law
F electric  k C (
q 1q 2
r
2
)
Distance and amount of charge affect force
When two charges interact, there is a force
between them. This force creates potential
energy.
This electric PE is a form of mechanical
energy, like KE, GPE and PEelastic
PEelectric, like all energy and work is measured in
Joules, J
Potential Difference
The change of potential energy per charge
Measured in J/C or volts
Ohm’s Law
V = IR
Current:
How much charge passes in a given time
I = DQ/Dt = C/s = amps
a
Find equivalent resistance, current in circuit, current
in resistor a, power dissipated by a
Magnetic field lines come out of the north
and go into the south
Right Hand Rule for Current
Velocity of a “+” charge
B is the magnetic field
strength
Drawing Magnetic Fields
Magnetic Vectors have to be shown in 3D
Velocity of
charge (+)
Magnetic
field
strength
Magnetic Force