PH 102  Activities 
Winter 20092010 
1.  Monday, Nov. 16  class list, syllabus, labs  
Macroscopic and microscopic approaches to
thermodynamics Zeroth law of thermodynamics Various thermometers  metal rod, liquid in open container, liquid in closed container, wire or thermister Temperature scales  Fahrenheit, Celsius, Kelvin  and conversions between them Triple point of water  273.16 K at a vapor pressure of 4.58 torr Thermal expansion of solids in one and two dimensions Problem 13.18: Calculate the change of area of a rectangular plate when it is heated and its temperature increases by ΔT. Bimetallic strips, Demos: steel/brass strip heated in a flame; ball and ring 

2.  Wednesday, Nov. 18  
Thermal expansion of solids in three dimensions 
equation for the change of volume. Table 131 on p. 358. Video 1  "Thermal Expansion: Liquids", Video 2  "Phase Change Expansion: Ice Bomb" Video 3  "Thermal Expansion: Breaking Rod", Video 4  "Linear Expansion: Determination of Alpha" Ideal gases  Boyle's law, GayLussac's law, Charles' law Periodic Table Animation1 and Animation2 illustrate these laws Ideal gas law (Equation of State of an Ideal Gas) Universal gas constant: R = 8.314 J/molK = 0.08206 literatm/molK Avogadro's number: N_{A} = 6.022 x 10^{23} molecules/mol Boltzmann's constant: k = R/N_{A} = 1.38 x 10^{23} J/K Kinetic Theory of Gases, rms (root mean square) velocity, ave. KE per mole, ave. KE per molecule  
3.  Friday, Nov. 20  
Speed distribution of molecules in a gas  physlet
 After it comes up and runs for awhile, click on "Average" and watch
the graph evolve. Graph of distribution of velocities in a gas (N_{v} vs. v). Shows v_{rms}, v_{ave} and v_{p} (most probable). Video 5  "Kinetic Model: Temperature Effects on Gases", Video 6  "Cryogenics: Organic Materials" Review (Jacques) Charles law ... Demo  cool things with liquid nitrogen: balloon, banana, plant leaves, ... Video 7  "Induced Phase Change: Solid N_{2}" Evaporation... Maxwell velocity distribution, demo  glass of water, explanation via the graph... Relative humidity and vapor pressure Video 8  "Cryophorous: Cooling by Evaporation", Video 9  "Induced Phase Change: Boiling by Cooling" Video 10  "Condensation: Formation of a Cloud" Saturated vapor pressure (SVP), relative humidity (RH), partial pressure (PP), RH = 100*PP/SVP Demo  humidity gauge Fog, smog, vog (volcanic gas + fog)  CO_{2} and sulfur Problems from Chapter 13. Table 133 

4.  Monday, Nov. 23  Chapter 14  Heat  Q4  
Definitions: calorie, kilocalorie (= food
Calorie), Btu Conversions: 1 kcal = 4186 J, 1 Btu = 252 cal Mechanical equivalent of heat = J = 4.186 J/cal = W/Q (Joule's law) heat absorbed = Q = m c ΔT, where m = mass, c = specific heat, ΔT = temperature change, Table 141, p. 387 heat gained = heat lost (conservation of energy) latent heat of fusion of water = L_{F} = 79.7 cal/g (at 0^{o}C) latent heat of vaporization of water = L_{V} = 539 cal/g (at 100^{o}C) If a substance changes phase: heat gained (or lost) = mass x latent heat, Q = m L Problem: Drop ice cubes into some water. Calculate the final temperature. heat of combustion = heat given off in burning heat conduction  heat transfer occurs by molecular collisions with no net movement of the molecules rate of heat flow = H = Q/Δt = k A ΔT / l where k = thermal conductivity, A = area, l = thickness, Table 144, p. 396 Demo  touch metal, then an insulator (like wood) at the same temperature  which feels colder? Video 11  "Thermal Conduction: Propagation in a Metal Rod", Video 12  "Thermal Conductivity: A Two Rod Combination" 

5.  Wednesday, Nov. 25  Q5  
Rvalue = R
= l / k, rate of
heat flow = H = Q / Δt = A
ΔT / R,
Table 145, p. 397 Review  various forms of energy ... (10 listed in class) Demo  happy ball, sad ball, energy conservation; push book along the table Heat is another form of energy: Q = mcΔT, Q = mL Three types of heat transfer: conduction, convection, radiation Convection: when "hot" molecules are physically transported from one region to another. Convection may be natural  caused by variations of fluid density in a gravity field, or forced  caused by a fan. Rate of heat flow = Q / Δt = h A ΔT Wind chill temperature index  chart (National Weather Service) Demo  Bunsen burner shadow... variation of air density Video 13  "Thermal Convection: Induced Fluid Flow", Video 14  "Thermal Convection: Projection of Currents". Radiation  heat is transferred from one molecule to another by electromagnetic waves. Thermograms  Fig. 1414, p. 402, human bodies Video 15  "Thermal Radiation: Transmission Using Parabolic Mirrors", Video 16  "Thermal Radiation: Black Body Effects", Video 17  "Thermal Radiation: Leslie's Cube". Problem 1444 on page 406. 

6.  Monday, Nov. 30  Chapter 15. The Laws of Thermodynamics  
The 1^{st} Law: All
the heat (energy) added to a closed system (constant mass) can be
accounted for as mechanical work, an increase in internal energy, or
both. In equation form: ΔU = Q
 W Various processes: isothermal, isometric, isobaric, adiabatic Internal energy of an ideal gas: U = 3/2 nRT Work = area under the PV curve For an adiabatic process, PV^{ γ} = constant Video 18  "Pressure and Temperature: Piston in a Cylinder". Human metabolism  conversion of internal energy (food  chemical energy) by an organism into other forms of energy: work, heat, waste products  metabolic rate (Table 155 on p. 415) varies like mass^{3/4} 

7.  Wednesday, Dec. 2  Q7  
Heat engines  a device for obtaining mechanical
work out of the heat energy of fuel  2stroke engine
(lawn mower, ...) 4 stroke gasoline engine (internal combustion)  Figure 1513, p. 417 Twocylinder four stroke motor Flash Physics Animations: 2 stroke engine, 4 stroke engine 2^{nd} Law of Thermodynamics Kelvin statement: It is impossible to construct an engine that, working in a cycle, has no effect other than the extraction of heat from a reservoir and the performance of an equal amount of work. Clausius statement: It is impossible to construct an engine that, working in a cycle, has no effect other than the transfer of heat from a colder to a hotter body. Coefficient of performance Entropy Problems from Chapter 14.  
8.  Friday, Dec. 4  
Review: 1^{st}
Law of Thermo, ΔU = Q 
W, Drawings for a Real Heat Engine and a
Real Refrigerator  
9.  Wednesday, Dec. 9  Chapter 16  Electric Charge and Electric Field  
Video 20
 "Electrostatics  Interaction of Charge", Video
21  "Distribution of Charge on a Conductor", Video 22  "Induction of Charge". Design and operation of an electroscope. Nine basic experimental results:
 
10.  Friday, Dec. 11  Q10  
The Triboelectric
Series  shows how strongly various materials hang on to
their electrons when you rub them together. List of items from Wednesday plus a few others, in order from most positive to most negative:
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 = F_{e } q = k Q/r^{2} Technique for tracing electric field lines Result: electric field lines always originate on positive charges and end on negative charges. Fig. 1630, Fig. 1631 Computer drawings  EM Field program  3D sources  electric field vectors (E) and electric field lines  
11.  Monday, Dec. 14  Went over Test 1  
Video 23  "Corona Discharge
 Electronic Precipitator", Video
24  "Electric Fields: Mapping of Force
Fields" 

Wednesday, Dec. 16  
Potential difference  gravitational and electrical Electric potential difference, ΔV The "ground symbol", definition of voltage: potential difference with respect to ground. Over short distances, points connected by a (metal) wire are at the same potential (ΔV = 0). All points on the outside surface of a conductor are at the same potential. An equipotential surface is one for which all points are at the same potential. Around a point charge q, the equipotential surfaces are spherical shells. V = kq/r where r = radius of the shell. Equipotential surfaces are everywhere perpendicular to the lines of force (i.e. the electric field lines). Computer drawings  EM Field program  3D sources  electric potential, V Fig. 176, Fig. 177 For a charge q moving through a potential difference V, the change of potential energy is ΔPE = qV. Definition: 1 electron volt = (electron charge) (1 volt), That is, 1 eV = 1.60 x 10^{19} C x 1V = 1.60 x 10^{19} J. Corona discharge  discharge of a conductor into the air producing a visible glow or spark. Demo  high voltage source Problems from Chapter 16.  
Friday, Dec. 18  Q13  
Capacitors  Any two conductors separated from one another by an insulator is a capacitor.  
14.  Monday, Jan. 11  
Demo  high voltage (1000 V) applied to 5
capacitors in parallel (26 mF)  BOOM!  release of 13 J Video 29  "Energy Stored in a Capacitor" Explanation of a cathode ray tube (CRT)  oscilloscope  Fig. 1720 on p. 486, TV  Fig. 1721. Chapter 18  Electric Currents Explanation of a zinccarbon battery Definition of emf (electromotive force)  a source of emf is any device that will transform nonelectrical energy into electrical energy. e.g. battery, electric generator, solar cell Video 30  "Operation of a Battery" Definition  electric current = I = ΔQ / Δt , unit for current: ampere (A). 1 A = 1 C/s Analogy: fluid flow  electric circuit 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 per 5.5 hours! 

Wednesday, Jan. 13  
(Georg) Ohm's Law 
resistance = voltage / current 

Friday, Jan. 15  Q16  
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, T_{c}. Graph of R vs. T. Use a 4point connection to avoid measuring contact resistance  demo Superconductivity discoveries: 1. In 1911 in mercury by KamerlinghOnnes (T_{c} = 4.15 K) 2. In 1986 in La_{2}CuO_{4} by Karl Muller and George Bednorz (who received the Nobel prize) (T_{c} = 35 K) 3. In 1987 in YBa_{2}Cu_{3}O_{7} (this is also called the "123 superconductor") by two groups (T_{c} = 92 K). Demo  magnetic levitation with a 123 disk, a styrofoam boat, liquid nitrogen (T = 77 K) and a small magnet. Video 32  "Superconductivity: Zero Resistance and the Meissner Effect" Theory of superconductivity  Hyperphysics  Georgia State University  C. R. Nave Superconductors Web site  includes the history Superconductivity applications: 1. At Fermilab magnetic windings (wires) are cooled with liquid helium (4.2 K) so the wires are below T_{c} resulting in a tremendous savings in electricity (practically no "Joule heating"). The magnetic field of each 7meter tubular magnet is 4.5 tesla. 2. "maglev" (magnetic leviation) trains in Japan, Germany and China (Shanghai). 3. Superconducting magnet in Science 114  part of the 400MHz 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 niobiumtitanium clad in copper. This is a Type II superconductor with a critical temperature T_{c} = 10 K. NMR slides taken Jan. 20, 2004. NMR cutaways  JEOL Unassigned problem  189 on page 516. 

Wednesday, Jan. 20  
Chapter 19. DC 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 E and I, calculate R Demo: add a second resistance box. Results: spreadsheet with graph 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: R_{s} = R_{1} + R_{2} + R_{3 }Resistors in parallel: 1/R_{p} = 1/R_{1} + 1/R_{2} + 1/R_{3 } Demo: three resistors (33 ohm, 56 ohm and 100 ohm) placed in series and then parallel  measure R 

Friday, Jan. 22  
Video 33  "Series and Parallel Circuits" "Use of a Working Hypothesis"  series and parallel Combining emfs in series and in parallel Example of using Kirchhoff's rules  3 equations in 3 unknowns


19.  Monday, Jan. 25  
Chapter 20  Magnetism A magnetic field is caused by moving charges  Lorentz force equation  F_{m} = q v x B Diagram showing magnetic field lines for several kinds of magnets  bar, neodynium, horseshoe Demo  zinc coated iron fillings on overhead, magnetic field lines  applet Video 34  "Mapping Magnetic Field Lines" (magnetic declination) = (direction of true north)  (direction of magnetic north)  map (Figure 3) Dip needle  here in the Quad Cities we are currently at about 55 degrees and the (magnetic declination) = 2^{o}E. Cross product of two vectors A and B: C = A x B, three ways to find the direction of C ... Magnitude of F_{m} = q v B sin θ Video 35  "Forces on an Electron Beam" 

Wednesday, Jan. 27  
Demo: Three glass tubes have a high
voltage applied creating a plasma (bluish glow due to ionization of air
molecules), deflect the beam with a magnetic field, round tube shows some
fluorescence (green) when electrons hit the glass 

Friday, Jan. 29  
Examples: the Tevatron at Fermilab
and the Large
Hadron Collider at CERN v not parallel to B: spiral path. Occurs in nature around B_{Earth}  produces the aurora borealis photos of Nov. 5, 2001  SpaceWeather.com  Aurorawebcam.com Hall effect, Hall voltage = V = v_{d }B l Demo: digital Tesla meter, magnet...
Torque on a current loop (suspended vertically) in a magnetic field, τ = N I A B sin θ How does a DC electric motor work? Demo: function generator  speaker  square wave  low frequency How does a loudspeaker work? Fig. 2038 

22.  Monday, Feb. 1 Q22  
Chapter 21. Electromagnetic Induction and
Faraday's Law  AC Circuits 

Wednesday, Feb. 3  
Motional emf,
induced current in a circuit Applications: recording and playback heads in tape recorders, VCRs, floppy disks, hard disks Electric generator (dynamo), motor  electrical to mechanical, generator  mechanical to electrical Fig. 2115 and Fig. 2117. An ac generator. Generator theory: ξ = N B A ω sin (ω t), ω = the angular frequency (in rad/s), ω = 2 π f, f = frequency in Hz. Demo: generator #1  incandescent bulb (digital multimeter to measure ac volts), flicker bulb 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 (pelteeyay) effect  turn crank one way (hot) and then the other (cold). This is how the Coleman thermoelectric heat pump works. Ring launcher  various rings  demo 

Friday, Feb. 5  
Solenoid doorbell (p. 567) Fig. 2027 Demo: run a DC generator backwards  its a DC motor! Alternator  demo  show an actual automobile alternator Transformers  Java applet  show examples  Fig. 2125. Video 38  "Voltage Transformer" Eddy currents are circular currents induced in the plane of a metal plate when passing through a changing magnetic field. Demo: aluminum plate on a wooden pendulum swinging through a strong magnetic field Video 39  "Eddy Currents: Force Acting on a Moving Conductor" Inductance, L Demo: various inductors (coils), measure with a digital LRC meter From experiment, induced emf = ξ =  L ΔI / Δt Combine with Faraday's law to get L = NBA / I For a solenoid: B = μ_{0}n I so L = μ_{0}N^{2}A / l Energy (in joules) stored in a coil (inductor), i.e. in a magnetic field: U = ½ L I^{ 2 }LR circuit (battery, switch, inductor and resistor in series) Equation for I ..., time constant = τ = L / R


25.  Monday, Feb. 8  
Demo
 all in parallel: function generator, resistor (100
Ω),
speaker (8 Ω),
DMM (ac volts), oscilloscope Results: DMM (digital multimeter) reads V_{rms} = 0.707 volts The oscilloscope displays the sine wave with amplitude = V_{0} = 1.00 volts (average power delivered) = P_{ave} = I_{rms}^{2} R = V_{rms} I_{rms} Chapter 21. Sections 1214. (inductive reactance) = X_{L} = 2π f L Fig. 2136 (capacitive reactance) = X_{C} = 1/(2π f C) Fig. 2137
RLC series circuit
Fig. 2139 

Wednesday, Feb. 10  
Chapter 22. Electromagnetic Waves
In 1865 James Clerk Maxwell published a
set of
four equations that basically unified electricity and magnetism. There will be one or two questions on Test 3 about what you learn from this video.
 
Friday, Feb. 12  
Video: "Tesla  Master of Lightning" 
watch the remainder. 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 of the Tesla coil  demo Tesla unit (1960) 
Last update: Feb. 9, 2010 