PHYS 203

Class Activities

Spring 2010

1. Monday, Mar. 8 - Chapter 21 - Electric Charge
  Video 1 - "Electrostatics - Interaction of Charge", Video 2 - "Distribution of Charge on a Conductor",
Video 3 - "Induction of Charge".
Design and operation of an electroscope.
Nine basic experimental results:

1.  Electric charges are of two kinds, positive and negative.
2.  Like charges repel each other and unlike charges attract each other.    Fig. 21-2
3.  Substances differ in electrical conductivity:  (a) conductors - have many "free" electrons,
     (b) insulators - have very few free electrons, (c) semiconductors - have some free electrons.
4.  The surplus charge on a solid or hollow conductor resides entirely on its exterior surface.
5.  Electric charge concentrates at edges and pointed surfaces on a conductor.
6.  When charges are separated by contact (rubbing things together), equal amounts of positive and negative
     charge are produced.  This is the Law of Conservation of Charge.  (Charge can be moved around but it cannot
     be created or destroyed.)
7.  Electric forces act at a distance.
8.  A body can be charged by conduction or induction.
9.  Higher humidity increases charge "leakage".    water molecule   Fig. 22-18

Demos:  (a) charged plastic box picks up shredded paper, (b) charge an electroscope by conduction and later by induction using various items - glass rod (+) and silk (-), PVC (-) and fur (+), (c) a charged balloon (rubbed on fur) "hangs" on a wooden door - and maybe other things, (d) a charged rod is brought near a falling thin stream of water - and deflects it - via induction.
2. Wednesday, Mar. 10
  Triboelectric Series - shows how strongly various materials hang on to their electrons when you rub them together.
List of items from Monday plus a few others, in order from most positive to most negative:
 
 Triboelectric Series
  1. dry human hands (+)
  2. animal fur (+)
  3. glass rod (+)
  4. acrylic (+)
  5. nylon (+)
  6. wool (+)
  7. silk (+)
  8. paper
  9. cotton
10. wood
11. steel
12. amber (-)
13. rubber rod (-)
14. brass, silver (-)
15. polyester
16. styrene (Styrofoam)
17. saran wrap
18. polyurethane
19. polyethylene (like scotch tape)
20. polypropylene 
21. vinyl (PVC) (-)
22. silicon
23. Teflon (very negative)

From Monday

Common experience
13. tennis shoes (-)  and  5. carpet (+)    13 - 5 = 8

Video
21. PVC rod (-)  and  2. animal fur (+)   21 - 2 = 19
7. silk (-)  and  4. acrylic rod (+)   7 - 4 = 3

Others
12. amber rod (-)  and  9. cloth (+)     12 - 9 = 3

Classroom demos
7. silk (-)  and  3. glass rod (+)   7 - 3 = 4
13. rubber rod (-)  and  2. animal fur(+)   13 - 2 = 11


Add another pair today.  demo

20. transparency (-)  and  8. paper (+)    20 - 8 = 12

Coulomb's Law - what you use to calculate the force between pairs of charges
Superposition Principle - For multiple charges, the vector force on each one is the sum of the vector forces from all the others.
Charge and mass of the (1) electron, (2) neutron, and (3) proton
Analogy:  force between masses ---- force between charges
Definition of an electric field,
E  =  Fe /q  = k Q/r2
Technique for tracing electric field lines
    Result: electric field lines always originate on positive charges and end on negative charges
Video 4.  "Corona Discharge - Electronic Precipitator".  Smoke particles are removed from a glass cylinder.
Video 5.  "Electric Fields:  Mapping of Force Fields"

3. Friday, Mar. 12
 

Computer - EM Field program - 3D sources (Start, Physics, EM Fields) - also available on the computers in 204 and 121
1.  Electric field of a discrete group of charges - add the E vectors from each charge
2.  E for a continuous charge distribution - a vector integral
Notation: Q = total charge, V = volume, A = surface area, s = length of a line (might be curved or straight)
                 volume charge density = rho =
ρ = Q/V
                 surface charge density = sigma =
σ = Q/A
                 linear charge density = lambda =
λ = Q/s
1.  Determine E for a "half-ring of charge" using calculus
2.  E for an electric dipole (+q and -q separated by a distance d),  dipole moment = p = qdE(z) = 2kp/z3     Fig. 22-8
3.  E on the axis of a charged ring   (Eq. 22-16)    Fig. 22-10
4.  E on the axis of a charged disk  (Eq. 22-26)    Fig. 22-13

4. Monday, Mar. 15
  Motion of a charged particle in a uniform electric field
Applications: oscilloscope, shadow of an electron beam, TV, computer monitor, ink jet printing (p. 592, Fig. 22-15)
Video 6. "Corona Discharge: Detection of Electric Wind".
Video 7. "Momentum of an Electron: Motion Imparted During Collision".
Dipole in an electric field - resulting torque.  Potential energy of a dipole     Fig. 22-19

Chapter 23. Gauss' Law -- electric flux, Φ = E A cos θ  = ... (integral of E dot dA)
S
pherical surface, Φ = q / ε0  where  q  is the enclosed charge

5. Wednesday, Mar. 17
  Gauss' law:  For any closed surface, electric flux = Φc = qin / ε0  where  qin  is the total enclosed charge
Computer - EM Field - 2D Charged Rods (with Gauss' Law)
Applications of Gauss' Law: 
1.  Insulating sphere of radius a and total charge QE = kQ/r2 (outside), E = (kQ/a3)r  (inside)
2.  Thin spherical shell with total charge QE = kQ/r2 (outside), E = 0 (inside)
3.  Infinite line of charge of linear charge density
λE = 2k λ / r.      Fig. 23-12
     Computer - EM Field - Options, Display Gauss' Law.
4.  Nonconducting, infinite plane sheet with surface charge density
σ.  E = σ/2ε0 (indep. of r)     Fig. 23-15
5.  Conducting surface with surface charge density σ.   E = σ/ε
0 (indep. of r)      Fig. 23-10
6. Friday, Mar. 19
  Chapter 24.  Electric Potential.
Analogy:  gravitational field --- electric field
Definition of potential difference,
ΔV = ΔU / qo = ...,  E = - grad (V)
   units:  1 volt = 1 joule/C, electric field: 1 N/C = 1 V/m
Electric potential of a point charge qV = kq / r
Video 8. "Electromagnetic Shielding".  Video 9. "Electricity Demonstrations".
7. Monday, Mar. 22
  Applications of Electrostatics
Xerography - invented by Chester F. Carlson in 1937.  How Photocopiers Work - How Laser Printers Work
Lightning - one minute exposure at Kitt Peak National Observatory in Arizona
Night lightning on Jupiter - cloud tops illuminated by sunlight reflected from the moon Io - photos taken by the spacecraft Galileo in October, 1997.
Van de Graaff generator - transparency, schematic drawing  -  Demo: stack of aluminum plates, blue-gold wig, spinner
Plasma globe - A partially evacuated glass sphere containing a mixture of inert gases.  When turned on, these gases become a plasma - a mixture of free electrons and bare atomic nuclei.  The smaller glass sphere at the center contains a power source similar to a Tesla coil.  It supplies and alternating, high voltage, high frequency, yet small current to the inner sphere. - Demo:  touch it, bring a neon tube near to it, look at the light though a diffraction grating  
Potential difference:  ΔV = ΔU / qo = - Ed, symbol for ground, equipotential surfaces
8. Wednesday, Mar. 24
  Computer - EM Field - equipotential lines
Recall: 
ΔU = q ΔV
Definition:  1 electron volt (eV) = 1.60 x 10-19 J   (energy conversion factor)
Corona discharge - discharge of a conductor at a high potential into the air producing a visible glow or spark     Fig. 22-16
Demo - induction coil
Video 10. "Corona Discharge - Lightning Model".  Demonstrates the physical basis of lightning by means of a model.  Summary:  An electric field is created between parallel plates.  Initially, sparks jump (via ionized air) from the upper negative plate to the round metal sphere placed near it.  Then a short, pointed metal rod is placed just to the left of the sphere.  At its tip there is a strong electric field and very rapid ionization.  The steady flow of ionized particles drains charge from the upper plate to the lower plate at a rate fast enough to keep the overall E field below the level needed to initiate an arc to the round metal sphere.  This illustrates the protective function of lightning rods.
Footnotes on the video:
At any given point in time there are about 2000 thunderstorms in action around the globe.  Instantaneous current generated by a single bolt of lightning can reach a magnitude as high as 20,000 A.
A typical flash of lightning results in a total transfer of around -25 C of charge from cloud to ground.  The energy dissipated in the lightning channel is roughly 109 J, most of which is converted to heat.  A small fraction goes into emission of light and radio waves.
Chapter 25.  Capacitance
Capacitor - any two conductors separated from one another by an insulator
Definition:  C = Q/V,  capacitance is measured in farads (F),  1 F = 1 C/V
Parallel plate capacitor drawing...
Demo - Pasco aluminum plates - one fixed, the other moveable on a track
E = V/d, symbols for a capacitor...,  C =
εoA/d
Isolated spherical conductor of radius RC = R/k
Derivation for a cylindrical capacitor
Derivation for a spherical capacitor

9. Monday, Mar. 29
  Capacitors with dielectrics, C = κ εo A/d = κ Co, κ = the dielectric constant      Table 25-1
Fig. 25-15 - Molecules with a permanent electric dipole moment. (a) no external E, (b) E applied
Fig. 25-16 - A non-polar dielectric slab. (a) dielectric slab, (b) apply E0, (c) net electric field E is smaller
                    so V is smaller and C increases with a dielectric present
Demo - large aluminum capacitor with (a) air, (b) bakelite, (c) cardboard
Video 11. "Parallel Plate Capacitor".
Show and discuss a variety of kinds of capacitors
Capacitors in parallel and series
Flash attachment - energy stored in the capacitor C1 is quickly dissipated via ionization of the xenon gas
      and subsequent emission of light.  Flash duration = 0.4 ms, cycle time = 0.3 s.
Energy stored in capacitors = U = ½ CV2
10. Wednesday, Mar. 31
  Add a dielectric to a capacitor:  U = U0/κ
High speed photography - independent study at Augustana in 1996 by Christopher Boldt
                                           and Scott Nowicki - apple - egg - water balloon
Demo - 13 J in five capacitors - boom !
Video 12:  "Energy Stored in a Capacitor"
Chapter 26.  Current and Resistance
Carbon/zinc battery - electrolyte - sulfuric acid
  emf (electromotive force) - a source of emf is any device that will transform non-electrical energy into electrical energy.
           e.g. battery, electric generator, solar cell
Video 13:  "Operation of a Battery"
Definition of current: i = dq/dt.   unit for current: ampere (A). 1 A = 1 C/s
Analogy: water pipe system with a pump, electric circuit with a battery.
Definition - the direction of conventional current flow is opposite to the direction the electrons flow
Drift velocity - it is extremely slow - typically about 1 m/h for i = 10 A
Two forms of Georg Ohm's Law:  J =
σE, V = i R
Resistivity
ρ of a wire of length L, cross-sectional area A and resistance R, R = ρ L / A.    Table 26-1     Table for α
Variation or resistivity with temperature, demo: heat a resistor, meas. R with the 4-digit DMM, it decreases slightly
11. Wednesday, Apr. 7
  Video 14:  "Temperature and Resistance"
Color codes for resistors:

Resistor Color Code Chart

1st & 2nd color band Digit

Multiplier

Tolerance

BLACK 0

1

 
BROWN 1 10  
RED

2

100  
ORANGE 3 1,000 or 1K  
YELLOW 4 10,000 or 10K  
GREEN 5

100,000 or 100K

 
BLUE 6 1,000,000 or 1M  
VIOLET 7 --  
GRAY 8 --  
WHITE

9

--

 
GOLD

--

0.10 5 %
SILVER

--

0.01 10 %
none -- -- 20 %

Joule's Law for resistors:  P = i2R = Vi = V2/R
Fuses and circuit breaker
Three-way switches, four-way switches
Demo - Electrocuting a Hot Dog.  So what is in hot dogs to make them behave like semiconductors?
Superconductors - materials for which the resistivity 
ρ  becomes zero as you lower the temperature through the phase transition temperature, Tc.   Graph of R vs. T.
4-point connection to avoid measuring contact resistance (Demo - used in PHYS 352, Advanced Lab) 
Discoveries:
    1.  In 1911 in mercury (Tc = 4.15 K) by Kamerlingh-Onnes.
    2.  In 1986 in La2CuO4 (Tc = 35 K) by Karl Müller and George Bednorz (Nobel Prize in Physics in 1987).
    3.  In 1987 in Y Ba2 Cu3 O7  (this is also called the "1-2-3 superconductor") (Tc = 92 K) by two groups.
Demo - magnetic levitation using a 1-2-3 disk, a Styrofoam boat, liquid nitrogen (T = 77K) and a small magnet.
Video 15:  "Superconductivity"   photo    Meissner effect
Theory of superconductivity - Hyperphysics - Georgia State University - C. R. Nave
Superconductors Web site - includes the history

12. Friday, Apr. 9
  Superconductivity applications:
  1.  At Fermilab magnetic windings (wires) are cooled with liquid helium (4.2 K) so the wires are below  Tc  resulting in
       a tremendous savings in electricity (practically no "Joule heating").  The magnetic field of each 7-meter tubular
       magnet is 4.5 tesla.
  2.  "maglev" (magnetic levitation) trains in Japan, Germany and China (Shanghai).

  3.  Superconducting magnet in Science 114 - part of the 400-MHz NMR (nuclear magnetic resonance) equipment.  The
       outer part is cooled by liquid nitrogen (77 K).  The inner part is cooled by liquid helium (4.2 K).  The magnetic field is
       very strong (9.7 tesla) and is well regulated.  This field is created by means of a solenoid (coil of wire).  The wire
       consists of very fine strands of superconducting niobium-titanium clad in copper.  This is a Type II superconductor
       with a critical temperature Tc = 10 K.  NMR slides taken Jan. 20, 2004.  NMR cutaways - JEOL

Chapter 27.  Circuits
Kirchhoff's First (junction) Rule:  The algebraic sum of the currents at any junction in a circuit is zero.
Kirchhoff's Second (loop) Rule:  The algebraic sum of the changes in potential around any closed path in a circuit is zero.
Potential difference in a circuit - resistors, batteries
Demo:  6V battery, (variable) resistance box, two DMM's, wires -  measure  ξ  and  i, calculate R
Demo:  Add a second resistance box.   Results:  spreadsheet - add graph

13. Monday, Apr. 12 - went over Test 1
  Example of using Kirchhoff's rules - two batteries, 7 resistors
Internal battery resistance (ranges from 0.05 ohms for new batteries to 100 ohms for old ones)
Resistors in series:  Rs = R1 + R2 + R3
Resistors in parallel:  1/Rp = 1/R1 + 1/R2 + 1/R3
Demo:  Three resistors (33 ohm, 56 ohm and 100 ohm) placed in series and then parallel  - measure R

Video 16:  "Series and Parallel Circuits"   This video (done by high school physics teacher and author Paul Hewitt) uses a 12 volt automobile battery.  It shows what happens when several standard automobile bulbs are placed in series and then in parallel.
Discussion, Tuesday, Apr. 13
  Example of using Kirchhoff's rules - 3 equations in 3 unknowns
Program Kirch
! A True BASIC program that solves circuit problems using Kirchhoff's rules.
dim A(3,3), B(3,3),
i(3), V(3)
mat read A         ! read the coefficients
data -1,1,1          !      -
i1 +    i2     +  i3   =    0
data  6,0,3          ! 
    6 i1               + 3 i3   =   24
data  6,6,0          !     6 i1 + 6 i2                  =   36
mat read V          ! read the voltages
data 0, 24, 36
mat B = inv (A)    ! find the inverse of matrix A
mat i = B * V       ! solution - calculate the currents
print "  The currents are:"
print "   
i1 = "; i(1)
print "   
i2 = "; i(2)
print "   
i3 = "; i(3)
end

When the program is RUN, the results are:

  The currents are:
    i
1 = 3.50
   
i2 = 2.50
   
i3 = 1.00                An Excel spreadsheet, a TI-83, and a TI-89 Titanium method for solving this same problem.

14. Wednesday, Apr. 14
  Combining emfs in series and in parallel, typical flashlight: two D cells (each 1.5 V) in series, various batteries
small 9 V battery: six internal 1.5 V cells in series, 12 V automobile battery: six 2.0 V cells in series but each cell has several dozen smaller 2 V cells in parallel (currents up to 50 A).
RC circuit, charging C, time constant  =
τ = RC, discharging C.
Demo on the computer:  Micasoft - M1 - capacitors

Chapter 28 - Magnetic Fields
Compare fields: gravitational, electric, magnetic
Magnetic fields of a bar magnet, a powerful neodymium (disk) magnet, and a horseshoe magnet, applet
Demo - magnets and zinc coated iron filings on overhead

15. Friday, Apr. 16
  Explore with the Magnaprobe.      Earth's magnetic field, Demo - ball (Earth) containing a magnet
Video 17:  "Mapping Magnetic Field Lines"
(magnetic declination) = (direction of true north) - (direction of magnetic north) = 2o east of north at Augustana     map
Dip needle to show the inclination -  here in the Quad Cities we are currently at about 55 degrees
Magnetic force on a moving charge, Fm = q v x B
Magnitude of Fm = qvB sin
θ, direction of Fm is perpendicular to the plane containing v and B.
Memory devices: 1. three-finger rule.  2. alternate right-hand rule.
Video 18:  "Forces on an Electron Beam"
Demo:  show the corresponding apparatus
Two special cases:  1. v parallel to B,   2. v perpendicular to B.     Uniform circular motion, r = mv / qB
Examples:  the Tevatron at Fermilab and the Large Hadron Collider at CERN
  If  v  is not parallel to  B: spiral path.  Occurs in nature around  BEarth - produces the aurora borealis     Fig. 28-12
photos of Nov. 5, 2001   |  SpaceWeather.com   |  Aurorawebcam.com
16. Monday, Apr. 19
  Force on a current segment in a magnetic field,  magnitude of the force = Fm = i L B sin θ  
Hall effect.   Hall voltage = V = vd B
l.   demo:  digital Tesla meter (to measure magnetic field)

Fractional quantum Hall effect
Nobel prize in physics in 1998
Dr. Daniel C. Tsui
Augustana graduate - 1961
Professor of Electrical Engineering at Princeton University
Book (in the Augustana library): "The Joy of the Search for Knowledge"
Scanning electron microscope room (115) named in his honor
Daniel and Linda Tsui Scholarship at Augustana College
Honorary degree from Augustana - May, 2004 - photos


Fig. 28-20 (electric motor).  Torque on a current loop in a magnetic field.   torque =
τ = N i A B sin θ.    DC electric motor
General form for a current loop:  torque vector =  τ = i A x B = μ x Bμ = i A = magnetic moment
Another torque application:  Galvanometer - add a coil spring.  Fig. 28-22

Chapter 29.  Magnetic Fields Due to Currents
Recall electric fields:  E = kq/r2.     Biot-Savart law...   Long straight wire:  B =
μ0i / 2πRFig 29-5.
Semi-infinite long wire: B =
μ0i / 4πR.
Center of a circular arc:  B =
μ0 i φ / 4πR.    Fig 29-6.   Center of a ring:  B = μ0 i / 2R

17. Wednesday, Apr. 21
  Two parallel current carrying wires
Video 19:  "Forces on a Current Carrying Wire"
Demo Current balance apparatus that will be used in lab
Magnetic field around a single current loop
Computer:  EMfield - magnetic field around a single current loop     Fig. 29-23
Current loop as a magnetic dipole,
μ = i A.   Compare to the magnetic field around a bar magnet:  Fig. 29-22
Ampere's Law - For any closed path around a one or more wires carrying a current,
       line integral ( B . ds ) =
μ0 ienc.   The integration loop is called an Amperian loop.
Computer:  EMField - explain Ampere's Law, file: isheets.emf
Magnetic field inside a long solenoid:  B
μ0 n i            n = no. of turns per meter
Demo:   
Fig. 29-19    Short solenoid, measure B with the digital Tesla meter    B = (0.5) μo n i (sin φ2 - sin φ1)
18. Friday, Apr. 23
  Toroid    Fig. 29-22    Computer:  EMfield - file: coaxmag.emf

Chapter 30.  Induction and Inductance
Oersted (1819) - an electric current produces a magnetic field
Michael Faraday (1829) - a magnet moving near a wire can produce an electric current
(Heinrich) Lenz's lawAn induced current has a direction such that the magnetic field due to the current opposes the change in magnetic flux that induces the current.
Fig. 30-1 and Fig. 30-4.  Thrust a bar magnet into a coil connected to a galvanometer (ammeter).
Fig. 30-2.  Two adjacent coils - one with an ammeter, the other with a battery, resistor and switch.
                Close and open the switch.
Demo - neodymium magnet, coil, galvanometer (document projector)       applet
Video 20:  "Induction of Current"
Definition:   magnetic flux  = 
ΦB  =  B A cos θ,   unit for flux:  weber (Wb)
Faraday's law of induction:  Induced emf  = 
ξ  =  - N d ΦB / dt  = - N d (BA cos θ) / dt 
So changes of B, A, or θ will produce an induced emf.
The negative sign reflects Lenz's law: "An induced emf always produces a current whose magnetic field opposes the original change of flux."  
Demo - Thrust magnet into a coil:  a. move faster, b. rotate coil.

19. Wednesday, Apr. 28
  Demo: Drop strong, small neodymium magnets into three tubes (PVC, aluminum, copper), time the fall, reverse the magnet.  Explanation...
Heliflux magnetometer - gift of Erick Schonstedt
Motional emf, induced current in a circuit,
ξ  =  B L v
Applications:  recording and playback heads in tape recorders, VCRs, floppy disks, hard disks, electric guitars
Electric generator (dynamo), motor - electrical to mechanical, generator - mechanical to electrical
ac generator (Fig. 31-6, p. 836)      Drawing and schematic - alternating current generator
  
ξ  =  N B A ω sin (ωt),     ω =  the angular frequency (in rad/s),  ω = 2πff = freq. in Hz
Demo:  generator #1 - incandescent bulb, flicker bulb
20. Friday, Apr. 30
  Demo:  generator #2 - (a) nothing - turns easily, (b) flashlight bulb, (c) a wire near a compass, (d) wrap the wire around the compass, what if there were several turns? (e) thermoelectric heat pump - Peltier (pelt-ee-yay) effect - turn crank one way (hot) and then the other (cold).  This is how the Coleman thermoelectric heat pump works.
How does a loudspeaker work?
Ring launcher - induced current in the ring such that its magnetic field opposes the magnetic field of the solenoid that created it.  Its like two magnets repelling each other, and the ring flies up.  Demo - several variations
21. Monday, May 3
  Demo: run a DC generator backwards - its a DC motor!
Eddy currents are circular currents induced in the plane of a metal plate when passing through a changing magnetic field. 
Video 21:  "Eddy Currents:  Force Acting on a Moving Conductor".
Current Balance Experiment - two horseshoe magnets - aluminum plate is a damper
Inductance of an inductor: L = N
ΦB / i    demo - digital inductance meter
Value of L depends on the geometry:  L =
μ0N2 A / l
RL circuit.  Fig. 30-18   Differential equation for the circuit, solution for the current,
   graph, inductive time constant =
τL = L / R
Computer:  Micasoft - M1 - inductors
Energy in a magnetic field, UB = 1/2 L i2, energy density in inductors and capacitors
Mutual inductance (when you have two coils)       Fig. 30-23
22. Wednesday, May 5
 
Chapter 31.  Electromagnetic Oscillations and Alternating Currents
LC circuit - electromagnetic oscillator, comparison to a mechanical oscillator   Fig. 31-1
RLC circuit, alternating current.  Graph - i and i2  (created with Origin - File, New, Function)
   rms (root mean square) value, rms current = Irms = 0.707 Im,
   rms voltage = Vrms = 0.707 Vm 
AC instruments:  an oscilloscope displays the instantaneous voltage v
             and the amplitude Vm.
A digital multimeter connected across R and set on ac volts reads Vrms
A digital multimeter connected in series with R and set on ac amps reads Irms
 


Fig. 31-5RLC Circuit.

23. Friday, May 7
 

Demo: R circuit - function generator, R, speaker, DMM (on ac volts), oscilloscope      Fig. 31-8 - R circut
Capacitor circuits:  capacitive reactance = XC = 1/
ωdC, VC = ICXC, vC lags iC by 90o     Fig. 31-9 - C circuit
Inductor circuits:  inductive reactance = XL =
ωdL, VL = ILXL, vL leads iL by 90o     Fig. 31-10  - L circuit 
RLC series circuit, i = Im sin
ωdt, phasor diagrams, impedance Z, V = IZ, Z = ..., tan φ = (XL-XC) / R
Resonance in an RLC series circuit, f = 1 / 2
π sqrt(LC), graph    Fig. 31-13, Demo: RLC circuit
Computer:  Micasoft - M1 - resonance
Power in AC circuits

24. Monday, May 10
  Transformers - Demo:  show several examples
Video 22: "Voltage Transformer"     Fig. 31-15
Power transmission from the power plant to the home - Transformer sequence

Chapter 32.  Maxwell's Equations, Magnetism of Matter
Induced magnetic fields, review of Faraday's law, Ampere's law, and both of Gauss' laws
Ampere-Maxwell law, summary - Maxwell's four equations - Table 32-1
Creation of electromagnetic waves (recall from PHYS 202)
Magnetic moment - current loop, electron in orbit, Bohr magneton
Magnetization M, magnetic field strength H, H = B/
μ0 - M = B0/μ0
   So  B =
μ0 (H + M)       units of H and M: A/m

25. Wednesday, May 12
  Curie's Law:  M = C (Bo / T), C = Curie constant, Bo = external magnetic field,T  = absolute temperature  Fig. 32-14
Properties of paramagnetic, ferromagnetic and diamagnetic materials
  M =
χ Hχ (chi) = magnetic suseptibility, p. 876: (paramagnetic) liquid oxygen suspended in a magnetic field  Ferromagnetism, magnetic domains   Fig. 32-17 (domains in nickel)

Video 23:  "Tesla - Master of Lightning" - We will watch the first part.  To be continued on Friday.
   
                        There will be one or two questions on Test 3 about what you learn from this video.

Go to the Web page Tesla - Life and Legacy to read more about each section of the video.
  1.  Tesla's Early Years
  2.  Coming to America
  3.  War of the Currents
  4.  Harnessing Niagara
  5.  High Frequency
  6.  The Wireless?
  7.  Race of Robots - Cosmic Waves
  8.  Colorado Springs
  9.  Tower of Dreams
 10.  Poet and Visionary - Modern Prometheus
 11.  The Mad Scientist
 12.  A Weapon to End War
 13.  The Missing Papers
7:20
6:52
4:43
4:17
6:37
5:39
4:32
5:26
6:57
4:57
4:20
7:45
11:10
 
14:12
18:55
23:12
29:49
35:28
40:00
45:26
52:23
57:20
61:40
69:25
80:35


Nikola Tesla at age 29.

26. Friday, May 14
  Video 23:  "Tesla - Master of Lightning" - We will watch the remaining 40 minutes.
Go to the Web page Tesla - Inside the Lab to obtain a description of Tesla's most important inventions:

    1.  AC Motor
    2.  Tesla Coil
    3.  Radio
    4.  Remote Control
    5.  Improved Lighting

Explanation and demo of the Tesla coil. 
Historical note:  Tesla coil Patent 454,622 - June 23, 1891.
Tesla unit (1960)

Last update:  May 13, 2010