Title: Introduction to Physical Systems Dr' E'J' Zita, The Evergreen State College, 30'Sept'02 Lab II Rm 22
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).