PHYS 115

You can find a copy of the questions we did in class here. Good luck on all your exams, and I wish you the best on the rest of your college career!

Posted directly from the source (Dr. Vogeley)

Final covers chs. 17-24. New material since midterm includes chs. 21-24

Ch. 21

Gauss's Law for electricity: include how to compute electric flux,how to construct a "Gaussian surface,"
** Why shape, size of surface doesn't matter (for fixed charge enclosed)

Application of Gauss's law to electric field inside/outside metals
** No E field inside conductors or inside holes in conductors - why?

Gauss's Law for magnetism: no magnetic monopoles!
** Trick question: what would this law look like if there were
magnetic monopoles?)

Ampere's Law: include how to compute integral of dot product of B with path, why path size, shape doesn't matter (for fixed current piercing the loop)

Applications of Ampere's Law: multiple wires (with different directions for I),
** solenoid

Differential forms of Maxwell's equations: no calculations necessary, but understand why these forms are useful/important
** they are LOCAL relations!

Ch. 22

Faraday's Law: direction of electric fields caused by varying magnetic fields? Get the sign correct!
How to compute magnetic flux?
How to compute path integral of electric field? Induced emf!
Time dependent mag flux depends on time dependent current (if produced by a current loop).
Again, get the sign correct.

Complications of Faraday's Law:
** Self-inductance (feedback) and implications for behavior of circuits
What happens if d^2I/dt^2\neq 0 (induced current varies, so varying B!)

Faraday's Law and Motional emf:
** mag flux can vary because of time varying B or A!

Inductance L of a coil (recognize the equation!)

RL circuit:
** Use loop rule to solve for I
What is time dependence of I?

LC circuit:
Use loop rule to solve for Q
** What is time dependence of Q, I (=dQ/dt)?
Why are Q, I out of phase?
** No equilibrium! What is long term behavior? Oscillation!
Period of oscillation of circuit

Ch. 23
Ampere-Maxwell Law:
** how to compute time-varying electric flux across capacitor

Complete version of Maxwell's equations:
** recognize which four eq's are the full versions!

Conditions for EM wave:
** How is direction of EM wave related to directions of E, B?
Relation between amplitudes of E, B fields E=cB

Accelerated charges make EM waves:
** recognize formula for E_{radiative} from a single accelerated charge dependence on perpendicular component of accelerating
** 1/r dependence

** Why doesn't the acceleration of the electron around the proton cause it to radiate away its energy and fall into the proton?

** Relations between wavelength, wavenumber, frequency, angular frequency, period, and velocity of a wave

** Energy density of EM radiation

Poynting vector carries energy of EM wave

Momentum flux related to Poynting vector, how?

EM waves interact with matter:
** E field transfers energy, but no momentum. How?
** B field transfers momentum. How?
What causes "radiation pressure" on matter?

What is "scattering"? (re-radiation, but in nearly all directions!)

Polarization:
** How do sunglasses work?
In which direction is sunlight reflected off water polarized?

Ch. 24

Again, relations between wavelength, etc.

Complete form of sinusoidal wave:
E(x,t)=E_0 \cos(\omega t - kx + \phi)
** Understand both spatial and temporal variation, meaning of phase
What is amplitude? Relation to Intensity (brightness)?

** Know definitions:
monochromatic, coherent, constructive interference, destructive interference

Path difference from two sources as fct of separation, angle

** Condition for constructive interference (integral wavelength path difference)
** Condition for desctructive interference (half-integral wavelength path difference)

** Know how to apply and combine formulae for path length difference and condition for interference (two-slit experiment)

Energy of a photon

** Give/recognize examples of wave-like, particle-like behavior of light

A copy of HW #7 can be found here.

Rec #6:
Tired of programming assignments? Lets forgo the computer today and think like experimentalist. Remember problem #1 in the latest homework? You are going to write an experimental proposal around this assignment. You've no doubt finished the assignment by now and come to the conclusion that the magnet drops slower through the pipe than a non-magnetized material. Why is this the case, and what happens to the energy? Can you measure this energy difference and where it goes? Since you can't see the magnet in the pipe, can you determine if the magnet reaches terminal velocity? Your job is to convince the (mathematically literate) layman of your claims. Your experiment should only consist of common everyday materials, and you must describe exactly how you use them. To get complete credit, you must fully prove to those watching the experiment all of your claims. You may assume that your audience is familiar with Maxwell's equations. Your explanation should consider things such as Maxwell's equations, friction, resistivity and specific heat.

The experimental proposal should be no shorter than one page in length (typed). While it is painful (and not necessary), it may be worthwhile to learn LaTeX to type the assignment. The rest of your future undergraduate physics career will require many typed submissions, so it is best to learn early.

A copy of HW #6 can be found here.

A copy of HW #5 can be found here.

Solutions to homework #4 can be found here.

Due Friday, May 4
Chapter 20:
Review questions 40, 41, Problems 44, 52, 62, 69

Again, next Wednesday's recitation section will be review for the midterm. The midterm itself will be given during recitation on Wednesday, May 9 and will cover through chapter 20.

Due Friday, April 27
Chapter 19:
Review questions 47, 55
Problems 61, 67, 69, 71, 73

Due Friday, April 20
Chapter 18: Review question 41 (Present a table with headings "experiment, effect on current, parameter." Explain your answers!)
Problems 45, 46, 50, 51 (also graph the potential V and electron current I for all at points A-F around the circuit), 56

Problems in Chapter 17 of Matter & Interactions II
17.P.43, 48, 49, 52, 55

I'm sure you know the drill by now, all rec. assignments must be emailed to me at hoppe@drexel.edu with your name included to receive full credit. If you need to contact the professor, Dr. Vogeley he can be reached at vogeley@drexel.edu. I hope the break was long and refreshing enough. If not then enjoy the breezy spring colors on this quarter's web page and I'll see all of you on Wednesday. Office hours are Monday 3-5 PM unless otherwise stated.

Prof. Michael S. Vogeley
Department of Physics
Office: 811 Disque Hall
Phone: 215-895-2710
Email: vogeley@drexel.edu

Grad Student: Travis Hoppe
Department of Physics
Office: 705 Disque Hall
Email: hoppe@drexel.edu

Announcements
Welcome to Physics 115: Contemporary Physics III! Get started by reading chapter 17 in MI2 (that's Matter & Interactions II - sorry Tom Cruise).

Course Meetings
Lecture times: Monday, Wednesday, and Friday 9:00-9:50 a.m. in Stratton 219. Please be on time (yes, we know it's early - bring coffee). Recitations: Wednesday 2:00-3:50 p.m. in Disque 704

Homework
Homework assignments will be due at the beginning of class on each Friday (except the first week and on the day of the midterm). Solutions will be available on the web page on that same day, so late homework will not be accepted. The computer assignments will count as one-third of your total homework grade and are due at recitation on the Wednesday following their assignment.

Grading
Homework: 30% (2/3 problems and 1/3 computer assignments)
Midterm: 25% (Midterm exam on Friday of week 5)
Final Exam: 35% (during exam week)
Class Participation: 10% (recitation!)

Description of this Course
In this final, and most fun of all, part of Contemporary Physics, we'll delve into further properties of electricity and magnetism. Topics include

• Magnetic Fields
• Electric Circuits
• Magnetic force (including the Hall Effect)
• Patterns of EM fields (focus on Gauss's Law)
• Faraday's Law
• Electromagnetic Radiation (yeah!)
• Waves and Particles (EM waves are also particles!)
• (if there's time) Semiconductor Physics

Reading
Chabay and Sherwood, Matter & Interactions II, 2nd Ed. In Physics 115, we will cover chapters 17-24 and, if time, discuss some topics in chapter 25.