Title: Introduction to Physical Systems Dr. E.J. Zita, The Evergreen State College, 30.Sept.02 Lab II Rm 2272, zita@evergreen.edu, 360-867-6853
1Introduction to Physical SystemsDr. E.J. Zita,
The Evergreen State College, 30.Sept.02Lab II Rm
2272, zita_at_evergreen.edu, 360-867-6853
Program syllabus, schedule, and details online at
http//academic.evergreen.edu/curricular/physys/06
07
Zita_at_evergreen.edu, 2272 Lab II TA Jada Maxwell
2Introduction to ElectromagnetismDr. E.J. Zita,
The Evergreen State College, 16.Jan.2007
- 4 realms of physics
- 4 fundamental forces
- 4 laws of EM
- statics and dynamics
- conservation laws
- EM waves
- potentials
- Ch.1 Vector analysis
- Ch.2 Electrostatics
34 realms of physics, 4 fundamental forces
4Four laws of electromagnetism
5Electrostatics
- Charges make E fields and forces
- charges make scalar potential differences dV
- E can be found from V
- Electric forces move charges
- Electric fields store energy (capacitance)
6Magnetostatics
- Currents make B fields
- currents make magnetic vector potential A
- B can be found from A
- Magnetic forces move charges and currents
- Magnetic fields store energy (inductance)
7Electrodynamics
- Changing E(t) make B(x)
- Changing B(t) make E(x)
- Wave equations for E and B
- Electromagnetic waves
- Motors and generators
- Dynamic Sun
8Some advanced topics
- Conservation laws
- Radiation
- waves in plasmas, magnetohydrodynamics
- Potentials and Fields
- Special relativity
9Ch.1 Vector Analysis
Dot product A.B Ax Bx Ay By Az Bz A B
cos q Cross product AxB A B sin q
10Examples of vector products
- Dot product work done by variable force
- Cross product
- angular momentum
- L r x mv
11Differential operator del
- Del differentiates each component of a vector.
- Gradient of a scalar function slope in each
direction - Divergence of vector dot product what flows
out - Curl of vector cross product circulation
12Practice 1.15 Calculate the divergence and
curl of v x2 x 3xz2 y - 2xz z
Ex If v E, then div E charge if v B,
then curl B current.
13Separation vector differs from position vector
Position vector location of a point with
respect to the origin.
Separation vector from SOURCE (e.g. a charge at
position r) TO POINT of interest (e.g. the place
where you want to find the field, at r).
14Ch.2 Electrostatics charges make electric
fields
- Charges make E fields and forces
- charges make scalar potential differences dV
- E can be found from V
- Electric forces move charges
- Electric fields store energy (capacitance)
15Gauss Law practice
What surface charge density does it take to make
Earths field of 100V/m? (RE6.4 x 106 m) 2.12
(p.75) Find (and sketch) the electric field E(r)
inside a uniformly charged sphere of charge
density r.
2.21 (p.82) Find the potential V(r) inside and
outside this sphere with total radius R and total
charge q. Use infinity as your reference point.
Compute the gradient of V in each region, and
check that it yields the correct field. Sketch
V(r).