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Announcements:
· Last day of class! Discussion: § Pass back quizzes. § Review. |
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Announcements:
· Quiz Review Problems (in green book): ° Ch. 35 Q: 13, 14, 15, 16, 17; P: 41, 43, 49, 51, 54, 55, 56, 59, 64; Discussion: § Present Group Problems § Take Quiz § Thin Lenses: |
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· Quiz Tomorrow (multiple choice over spherical and flat mirrors) Discussion: § HW Questions § Group Problems § Thin Lenses: |
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Announcements:
· Quiz Tuesday Homework: ° Ch. 35 Q: 2, 3, 4, 5; P: 1, 2, 3, 6, 9; Discussion: § Demo: Total Internal Reflection (Laser/Tube) § Spherical Mirrors: ° difference between concave and convex ° center of curvature, radius r ° central axis ° focus f-- intersection of incoming rays parallel to axis ° f = r/2 ° 1/p + 1/i = 1/f ° object height: h ° image height: h' ° magnification: |m| = h'/h ° m = - i / p ° negative magnification: image inverted § Finding Images: ° rays parallel to axis, reflect through focus ° rays through focus, reflect parallel to axis ° rays through center, reflect upon themselves ° rays through intersection of mirror w/ axis, reflect symmetrically |
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Announcements:
· Last Quiz next Tuesday Review Problems (in green book): ° Ch. 33 Q: P: 73; ° Ch. 34 Q: 16, 17, 19, 22; P: 69, 70, 81, 89, 92, 93; Discussion: § Finish group problems from Ch. 34 § Flat Mirrors: |
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Announcements:
· Last Quiz Thursday? Discussion: § Demo: § Dispersion: ° chromatic dispersion ° monochromatic light ° white light ° effect of a prism ° generation of a rainbow § Total Internal Reflection: ° only for going from high to low ° critical angle ° light reflected along interface ° practical applications § Group Problems |
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· Test Thursday · Review Session: Today 12:30pm (after class) Wednesday 4pm · Equation Sheet (PDF) for Test Discussion: § HW Questions § Group Problems |
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Announcements:
· Test Thursday · Schedule Review Session Homework: ° Ch. 31 Q: 6; P: 29, 33, 36, 37, 40, 41, 46, 47, 53bcd, 58, 59; Review Problems (in green book): ° Ch. 31 Q: 14, 19, 20, 21, 23, 36; P: 78, 87, 88, 98; Discussion: § Demo: Faraday's Law. § Inductance: ° analogous to capacitors: store magnetic field ° definition: flux per unit current ° new unit 1 heny = 1 H = T m^2 /A ° Example: solenoic: inductance per unit length ° Dependent only on geometry § Self Inducation: ° EMF induced within a single coil ° Can solve for value: ° Inductors in circuits produce potential differences § RL Circuits: ° Loop law gives differential equation ° Solve with no battery ° Exponential decay of current ° Different time constand tau = L/R § Energy Stored in Magnetic Field: ° Inductor stores in energy in magnetic field ° Multiply loop law by I and analyze § Group Problems |
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Announcements:
· Test in a week Homework: ° Ch. 31 Q: 1, 2, 3, 4; P: 1, 2, 3, 8, 9, 15, 19, 20, 24, 25, 28; Discussion: § Return quizzes. § Demo: Lenz's Law. § Faraday's Law: ° changing magnetic field can produce electric field/current ° magnetic flux instead of electric flux ° induced EMF is equal to rate of change of magnetic flux ° new unit § Lenz's Law: ° gives direction of induced emf ° induced emf opposes change in flux ° Method: ° (1) Describe change in flux: eg losing dots ° (2) Describe need: need more dots ° (3) Pick EMF to satisfy need § An Example: Energy Transfer § Eddy Currents: ° No single pathway exists (wire) ° Instead entire conducting area ° Induced an (eddy) current § Faraday's Law says electric field is induced § Electric Potential has no meaning for these electric fields |
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· Quiz Today Review Problems (in green book): ° Ch. 30 Q: 12, 14, 15, 16, 18; P: 60, 61, 65, 66, 69, 71, 72, 75, 76; Discussion: § Toroid: ° Bend a solenoid in a circle ° Symmetry says field lines are circles ° Ampere's Law gives us the magnetic field: ° Field is not uniform ° B = mu I N / 2 pi r § HW Questions § Group problems § Quiz |
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· Quiz Tomorrow · 2 Handouts Homework: ° Ch. 30 Q: 7, 8, 9; P: 31, 32, 35, 40, 41, 43, 46; Discussion: § Review of last week & HW questions § Ampere's Law: ° similar in purpose to Gauss's Law ° derives from Biot-Savart ° information from nature of field lines ° use right hand rule for sign ° Current produces magnetic field § Applying Ampere's Law: Long Wire ° outside: get same result as before ° inside: need to consider enclosed current § Solenoid: ° coil of wire ° field cancels and adds to approx. ideal ° ideal: zero outside, uniform and parallel inside ° direction: curl right fingers in direction of current, B in direction of thumb ° Ampere's Law gives us the magnetic field: § Demo § Toroid: ° Bend a solenoid in a circle ° Symmetry says field lines are circles ° Ampere's Law gives us the magnetic field: ° Field is not uniform § Group problems |
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Announcements:
· Test in Two Weeks · Quiz Tuesday Homework: ° Ch. 30 Q: 1, 2, 3, 4; P: 1, 2, 4, 5, 6, 9, 10, 19*, 21, 22, 23, 29; Review Problems (in green book): ° Ch. 29 Q: 12, 13, 14, 16, 17, 19; P: 62, 64, 70, 72; Discussion: § Pass back quizzes § Biot-Savart Law: ° Current produces magnetic field ° Law gives us dB due to small section of current ° Permeability constant § Applying Biot-Savart: Straight Wire ° Another right hand rule ° Derivation § Applying Biot-Savart: Arc of Wire ° Same right hand rule ° Derivation § Force Between Two Parallel Currents: |
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· Quiz Today Homework: Discussion: § Electric Motors/Generators § HW Questions § Present Group problems. |
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Announcements:
· Quiz Tuesday · Not responsible for 29-6, 29-8, 29-9 · Handout: Current Carrying Wire · Book: The Physics Toolbox on reserve at library Homework: ° Ch. 29 Q: 5, 6, 7; P: 15, 17, 19, 24, 33, 34, 35, 37; Discussion: § Deflection of moving particle Demo § Continue Ch. 29: Magnetic Fields § Hall Effect: ° Wire in magnetic field feels effect ° Moving electrons pile up on one side ° Magnetic and electric forces reach balance ° Creates potential difference in conductor ° Shows that negatives are charge carriers § Circulating Charged Particle: ° Shoot electrons with velocity perp to uniform B ° v and B remain perp-->circular motion ° magnetic force is centripetal force ° r = mv / q / B ° T = 2 pi m / q / B = 1 / f ° omega = 2 pi f = qB / m § Magnetic Force on Current Carrying Wire: ° Current consists of moving charges ° Hence, same force, different formula ° F = I L cross B § Begin group problems |
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Announcements:
· Return tests · Quiz Tuesday · Handout: RH Rule Homework: ° Ch. 29 Q: 1, 2, 3; P: 1, 3, 5, 7, 8, 9; Discussion: § Go over tests § Discuss grades § Begin Ch. 29: Magnetic Fields § Source of Magnetic Fields: ° magnetic monopoles--never found ° moving charges ° intrinisic property of electrons § Defining Magnetic Field: ° do so in terms of force and field, B ° can't do in same way as defining E-field ° experiments show: F = qv cross B ° Units: 1 Tesla = N/A/m ° 1 Tesla = 10^4 gauss ° Typical values for magnetic field § Field Demo § Review of Cross-Product: ° Mag: a cross b = c where c=ab sin phi ° Dir: right hand rule ° F always perp to v and B ° v and B not nec. perp § Magnetic Field Lines: ° Tangent indicate direction of B ° Line density indicates field strength ° Lines always close ° End where lines emerge: North ° End where lines enter: South ° Opposite magnetic poles attract § Compasses: ° Small bar magnet, low friction ° North-pole end points to Canada ° South-pole end points to Antarctica ° Earth's "(Geomagnetic) North/South Poles" § Crossed E & B Fields: ° crossed means E perp to B ° occurs in CRTs ° moving charge experiences two forces ° can be made to cancel |
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Homework: Discussion: § TEST |
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Announcements:
· Test Tomorrow · Date for Final: Tuesday, Dec. 16 at Noon Homework: Discussion: § Questions from HW § Present group problems |
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Announcements:
· Return Quizzes · Test Tuesday · Equation Sheet (PDF) for Test · Review Sessions: Today 1pm; Monday 3pm Homework: ° Ch. 28 Q: 6; P: 25, 26, 31, 33, 34, 44, 48; Review Problems (in green book): ° Ch. 28 Q: 12, 14, 15, 16, 18; P: 60, 63, 64, 69, 71, 72, 81; Discussion: § Questions from HW § Ammeter and Voltmeter § RC Circuits ° time constant tau = RC ° discharging (won't cover charging) § Group Problems |
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Announcements:
· Quiz Today Homework: ° Ch. 28 Q: 2, 3, 5 P: 2, 4, 5, 10, 13, 18, 19, 20, 21 Discussion: § Questions from HW § Last group problem § Quiz § Start Ch. 28: § EMF ° Work per unit charge ° Units of volts ° I = EMF/R § Kirchoff's Loop Law ° Sum of voltage drops in a loop is zero ° Works on any loop ° Have to be careful with signs ° For Resistors: · in direction of current arrow, -IR · against direction of current arrow, +IR ° For EMFs: · in direction of EMF arrow, +EMF · against direction of EMF arrow, -EMF § Potential Difference Between Points ° use same methods as for loop law ° start at one point and pick any path to other point ° add/subtract all potential differences § Resistors in Series § Resistors in Parallel § Multi-Loop Circuits |
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Announcements:
· No Lab Thursday and Monday; instead HW · No Lecture Monday, Oct. 20. · Return Quizzes · Quiz next Tuesday Homework: ° Ch. 27 Q: 9; P: 23, 31, 33, 35, 37, 40, 42; Review Problems (in green book): ° Ch. 27 Q: 17, 22, 28; P: 48, 49, 58b, 63; Discussion: § Questions from HW § Finish Ch. 27: § Ohm's Law ° Resistors: R indep. of voltage ° V=IR ° Can set V or or I, but not both § Power ° energy transfer: P=IV ° units ° difference between energy and power ° resistive losses: I^2 · R or V^2/R § Semiconductors ° resistivity large dependence on purity ° great for making devices ° heat big issue: move to diamond? § Superconductors ° zero resistivity for some temperature range ° hold great promise if: · high temperature · high current · magnetic field § Group problems |
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Announcements:
· No Lab Thursday and Monday; instead HW · No Lecture Monday, Oct. 20. · Will have lecture Thursday, Oct. 16. Homework: ° Ch. 27 Q: 1, 3, 4, 6a-c; P: 1, 3, 4a, 7, 12, 13, 15, 17, 20; Discussion: § Last group problem from Ch. 26 § Quiz 4 § Ch. 27: Current and Resistance § Electric current: ° net flow of charge ° I = dq/dt ° Units: A = C/s ° Produced by electric fields (battery or power supply) ° Scalars ... but have direction/signs ° conserved ° Arrows drawn in direction positives would go § Junction Law ° three or more wires joined ° current in equals current out § Current Density ° current per unit area ° tool for analyzing certain things ° I = int ( j dA) ...simple I = JA § Resistance & Resistivity § Effect of potential difference in circuit varies § Describe effect by resistance R = dV/dI § Units: 1 ohm = V/A § Resistance occurs lots of places § Resistors have symbol § Resistivity rho = E/J § Conductivity sigma = 1/rho § Difference between resistivity and resistance § R = rho L / A |
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Announcements:
· No Lab Thursday and Monday; instead HW · No Lecture Monday, Oct. 20. · Will have lecture Thursday, Oct. 16. · Quiz tomorrow Homework: Discussion: § Questions on HW § Present group problems |
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Announcements:
· Quiz next Tuesday Homework: ° Ch. 26 Q: 5, 6; P: 10, 11, 13, 15*, 18, 23, 25, 29; Review Problems (in green book): ° Ch. 26 Q: 12, 13; P: 49 (read), 54, 55, 56, 60, 68, 69, 71, 73; Discussion: § Demo § Capacitors in Parallel ° same voltage drop ° total charge is sum of charges ° eq. cap. is sum of capacitances § Capacitors in Series ° total voltage drop is sum of voltages ° same charge ° eq. cap. is inverse of sum of inverse cap's § Compound Circuits ° work forward to compute equivalent capacitance ° draw a series of pictures ° work backwards to find charges and voltages on ind. caps § Energy Stored in an Electric Field (ignore energy density) § Group Problem session |
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Announcements:
· Return Tests · Discuss grades · Ignore 26-6, 26-7, 26-8 Homework: ° Ch. 26 Q: 1, 2, 3, 4; P: 1, 2, 3, 4, 5, 6, 7, 8; Discussion: § Go over tests § Chapter 26: Capacitance § Demo § Capacitors: ° store energy in electric field ° Plates: conductors which hold charge ° When charged, plates have equal but opposite charges ° Everywhere on a plate, same potential ° Capacitance depends on geometry, not charge or pot. diff. ° Units: C/V = farad ° Assume can store indefinitely ° Discharges only when placed in circuit § Calculating Capacitance: ° Parallel Plate Capacitor ° Cylindrical Cap ° Spherical Cap ° Isolated Sphere § Capacitors in Circuits ° Incomplete circuits ° Closed circuits ° Equivalent Capacitance ° Circuit Components in Series ° Circuit Components in Parallel |
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· Test Today |
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Announcements:
· Test Thursday · Review sessions: Tue & Wed 4pm · Ignore 25-7 Homework: ° Ch. 25 Q: 6, 7, 8; P: 15, 25, 28, 30, 31, 37, 43, 47, 50; Discussion: § Questions on HW § Finish Chapter 25: Electric Potential § Charged Bodies: Line of charge § Charged Bodies: Charged disk § Electric Field from potential § Potential Energy of a system of charges § Isolated Conductor § Demo DVDs § Fake Quiz for Ch. 25 |
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· Test Thursday · Last year's short answer questions (PDF) · Equation Sheet (PDF) for Test · Review sessions: Tue & Wed 4pm Homework (Review Problems): ° Ch. 22 Q: 13, 14, 15, 18, 20, 21; P: 31, 34, 35, 38, 41; ° Ch. 23 Q: 13, 15, 17; P: 51, 56, 57, 63, 65; ° Ch. 24 Q: 12, 13, 14, 17, 19; P: 49, 53, 57, 58, 59, 61, 63, 68; ° Ch. 25 Q: 13, 15, 18; P: 62, 63, 64, 67, 69, 70, 71, 75; Discussion: § Questions on HW § Return Quizzes § Chapter 25: Electric Potential |
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· Quiz Today · Handout Homework: ° Ch. 25 Q: 2, 3, 5; P: 1, 2, 4, 5, 8, 13; Discussion: § Questions on HW § Quiz § Chapter 25: Electric Potential ° Electric Potential Energy ° Electrostatic force is conservative ° Electric Potential & Potential Difference ° Scalar not vector ° Unit: Volt ° Equipotential Surface: · Everywhere on it at same potential · Efield everywhere perpendicular to it ° V from E ° Potential from a Point Charge |
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Announcements:
· First entry in log. · No lab the first week of classes. · First quiz will be Thursday. |
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Announcements:
· First day of class. · No lab the first week of classes. · First quiz will be Thursday. Homework: ° Read Ch. 22 Discussion: § Hand out and go over syllabus. § Take pretest. § Hand out Wired article to discuss Tuesday. § Introduce electric charge. |
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Announcements:
· First quiz will be Thursday. Homework: ° Ch. 22: Q: 2, 3, 5, 6, 8, 11 P: 1, 3, 5, 10, 13, 19, 21, 23 Discussion: § Discuss pretest & Wired Article. § Net charge and charge balance § Electrostatics---charges move and quickly settle down § opposites attract & likes repel § conductors & insulators: induced charge § Coulomb's Law § Shell Theorems: inside and outside a uniform, spherical shell § Charge is quantized: e § Charge is conserved |
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· Will work Ch. 23 problems on Monday. · Ignore Section 23-9. Homework: ° Ch. 23: Q: 2, 5, 6; P: 1, 3, 5, 9, 11 Discussion: § Questions about Ch. 22 HW § Demo: Van de Graff generator § Take Quiz 1 § Start Ch. 23: § Why do we need to define an electric field? § What is a field? Scalar/vector field § Definition of electric field § A handy tool: field lines § Electric field of a point charge |
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· Tutor: Danielle Thibault M 10-12pm W 6-8pm · Student Solutions Manual in Library Reserve · Return Quizzes Homework: ° Discussion: § Questions about Homework § Understanding E-Field: field lines |
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· Handout · Quiz Thursday on Ch. 23 · Read Ch. 24 Homework: ° Ch. 23 Q: 7, 9; P: 18, 20, 21, 22, 23*, 24*, 27, 29, 41, 42 Discussion: § Review of Electric Field lines: ° lines point in direction positive charge would go ° density of lines indicates magnitude of E-field ° a charge would feel a force in direction tangent to E-field at its position ° originate at positive charge and terminate at negative charge ° we'll add a couple more things to this list in next chapter § Electric Field from Extended Bodies § Electric Field of Charged Ring § Electric Field of Charged Disk § Point Charge in Electric Field |
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· Quiz Today · Handout · Test in 2 weeks Homework: ° Ch. 24 Q: 1, 2, 4, 5, 6; P: 2, 3, 5, 6, 11 Discussion: § Questions before quiz § Quiz § Discuss Ch. 24 Gauss' Law: ° Makes certain situations simpler than integrating ° Gaussian Surface---close (defines inside/outside) ° Flux ° Electric Flux proportional to net number of efield lines passing through ° Gauss's Law ° Gauss's Law is equivalent to Coulomb's Law |
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· Quiz Thursday Homework: ° Discussion: § Questions from homework § Astroblaster demo § Discuss Gauss's Law for a conductor |
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Announcements:
· Quiz Thursday · Handout Homework: ° Ch. 24 Q: 7, 8, 10; P: 12, 15, 17, 19, 21, 28*, 35, 43; Discussion: § Electric Field just outside a conductor § Can you shield charge? § Line of Charge § Sheet of Charge § Gauss's Law for a Sphere: ° Prove the Shell Theorems ° Electric field inside solid sphere of charge § Problems to be worked in class |