Day 19

Wednesday, July 19, 2006

Announcements:

Exam 2 will be held next Monday, which is the same day as the Lab Exam for many of you. If you prefer to take the Lab Exam this Friday instead of on Monday, let me know so that I can make the necessary arrangements.
A student in this class (Zach Swan) has identified a website that has several useful Java Applets for selected physics topics. I have added a link to this website under the Resources section of the course webpage, and I encourage you to take a look at these as you prepare for your exams.
Several groups have already published their Web Project. Please check the list of Web Projects and let me know of any updates.
A solution to the Contact Lenses real-world problem has been posted. Be sure to examine this solution before the next exam.

Assignments:

Read Chapter 31 and submit HW31a before class tomorrow.
HW29b is due tonight at midnight
Web Projects are due this Friday, July 21. Send me your URL as soon as possible.

Chapter 29: Relativity

Special relativity deals with inertial frames of reference (a = 0)
General relativity (a <> 0)
    Examples of inertial and non-inertial reference frames: a) space ship traveling in a straight line, b) space shuttle in orbit, c) this classroom
Consequences of Special Relativity: As v -> c, several physical parameters change by factor of gamma = 1/sqrt(1-v^2/c^2)
    Ponderable: What are "relativistic" speeds? (see table below)
Time dilation: t = to*gamma
Length contraction: L = Lo/gamma
Mass increase: m = mo*gamma
Relativistic energy: E = mc^2 = gamma*Eo
Relativistic KE: K = Eo*gamma - Eo
General relativity:
    All physical experiments yield identical results in an accelerated reference frame as they do in a gravitational field.
Black holes: Light cannot escape a star with a radius less than or equal to the Schwarzschild radius: R = 2GM/c^2
Ponderable: If an astronaut travels 1 ly at 0.9c, why is t <> to*gamma?

Concept Tests - Chapter 26

Chapter 30: Quantum Physics

"The universe is not only stranger than we imagine, it is stranger than we can imagine."
This chapter synthesizes many concepts from previous chapters.
    Movie trailer from Down the Rabbit Hole: The Double Slit Experiment

30-1: Blackbody Radiation and Quantization
    An ideal blackbody does not reflect any light that hits it. Such a perfect absorber of radiant energy is also a perfect emitter (e = 1.00).
    The distribution of energy as a function of frequency only depends on the temperature of the blackbody:
    Wien's displacement law: f(peak) = wT, where w = 5.88x10¹⁰ s^-1K^-1Quantization of energy
    Examples of quantization
30-2: Photons and the Photoelectric Effect
Planck's constant and quantization: E_n = nhf
Photons and photoelectric effect - energy, work function, cutoff frequency, max K
   KE_max = E - W_o
30-3: Relativistic mass and momentum of photons
    Demo: Radiometer
30-4: Photon scattering and Compton effect
The de Broglie wavelength, wave-particle duality
    Wavelength and resolution
X-ray diffraction
30-5: Heisenberg uncertainty principle
30-6: Quantum Tunneling
    Scanning Tunneling Microscope (STM)

Concept Tests - Chapter 27