1. Textbook: 10.1 Homework: Read pg 494 – 498 Do: pg 498 # 1 – 5
Polarization
Textbook: 10.1
Homework: Read pg 494 – 498
Do: pg 498 # 1 – 5

2. EM Waves
Electromagnetic waves are transverse because they can be polarized
Light polarized in direction of E field

3. Unpolarized Light
Unpolarized light (or any EM waves) have both x & y components of the electric field vectors.

4. Polarized Light (EM waves)
Polarization is the removal of one component of the electric field.

5. Malus’ Law: The Intensity of Transmitted Light (through ONE filter)
I0 is the intensity of the incident light and I1 is the intensity of the ray exiting the polarizing filter.

6. Malus’ Law: The Intensity of Transmitted Light (through TWO filters)
I2 is the intensity of the ray of light emerging from the analyzer (the second Polaroid),
The polarizer produces polarized light. Rotating it doesn’t affect the intensity of light. The emerging light’s intensity is always ½ I0.
The analyzer determines the plane of polarization. Rotating the analyzer causes the intensity of the emerging light to vary.

7. Applications of Polarization
Glare: Light bouncing off a flat surface is partially polarized
Scattering: Light moving through a fluid (ex. Air) can be partially polarized
Calcite Crystals: Are doubly refractive (refractive index depends on polarization)
Photoelasticity: Some materials (lucite) polarize depending on stress on the material

8. Special Relativity Textbook: 11.1, 11.2, 11.3
Homework: pg. 568 # 5, 6;
pg. 579 # 1, 2, 6, 8, 9

9. Special Relativity Einstein’s Postulates:
The relativity principal: All of the laws of physics are valid in all inertial reference frames.
The Constancy of the Speed of Light: Light travels through empty space with a speed of c = 3.00 x 108 m/s, relative to all inertial reference frames.
Ex. Discuss simultaneity of events

10. Simultaneity
Two events that are simultaneous in one frame of reference are not necessarily simultaneous in another frame of reference
The order in which events occur depends on your frame of reference

11. Time Dilation A clock moving past an observer appears to run slow
ts = proper time (time measured when at rest with respect to clock)
tm = dilated time

12. Length Contractions
Since observers must agree on relative velocities, length must change based on the frame of reference.
Lm = Length between points A and B where A and B are moving with velocity v
Ls = Length between points A and B where A and B are stationary

13. Paradoxes The Curious Case of the Muon The Twin Paradox
Muon’s are elementary particles that are produced when our upper atmosphere is bombarded by cosmic rays
The Muon’s lifetime is very short (2.2 x 10^-6 s)
According to Newtonian mechanics even traveling at high speeds Muon’s should not get to the surface of the Earth
The Muon’s clock is running slow so it seems to last longer
In the Muon’s frame of reference the distance is contracted
The Twin Paradox
The twin that leaves ages at a slower rate than the twin that stays on Earth
The symmetry that we have seen is ruined because the twin in the shuttle has to accelerate
High acceleration causes your clock to run slower - MUCH slower
The Ladder in the Barn
How can one observer say that the ladder fits into the barn and the other says it doesn’t?
For one observer both ends are simultaneously inside the barn
The other observer does not see both ends inside the barn simultaneously

14. Pg 572
1. Are airline pilots’ watches running slow in comparison with clocks on the ground? Why or why not?
2. A beam of unknown elementary particles travels at a speed of 2.0 x 108 m/s. Their average lifetime in the beam is measured to be 1.6 x 10-8 s. Calculate their average lifetime when at rest. [1.2 x 10-8 s]
3. A Vulcan spacecraft has a speed of 0.600c with respect to Earth. The Vulcans determine 32.0 h to be the time interval between two events on Earth. What value would they determine for this time interval if their ship had a speed of 0.940c with respect to Earth? [75.0 h]
4. The K+ meson, a subatomic particle, has an average rest lifetime of 1.0 x 10-8 s. If the particle travels through the laboratory at 2.6 x 108 m/s, by how much has its lifetime, relative to the laboratory, increased? [2x]
x 10-8 s h
4. 2x

15. Pg 576
5. A spaceship passes you at the speed of 0.90c. You measure its length to be 50.0 m. What is its length when at rest? [115 m]
6. You are a space traveller, moving at 0.60c with respect to Earth, on your way to a star that is stationary relative to Earth. You measure the length of your trajectory to be 8.0 light-years (ly). Your friend makes the same journey at 0.80c with respect to Earth. What does your friend measure the length of the trajectory to be? [6.0 ly]
7. A spacecraft travels along a space station platform at 0.65c relative to the platform. An astronaut on the spacecraft determines the platform to be 3.00 x 102 m long. What is the length of the platform as measured by an observer on the platform? [3.95 x 102 m] m ly
x 102 m

16. 12.1 The Photoelectric Effect
Textbook: 12.1
Homework: pg. 597 – 598 # 1 – 5
pg. 604 # 7 – 15

17. Planck’s Constant
In 1900, German physicist Max Planck suggested that light travels in packets called quanta.
These packets define the amount of energy transferred by a given frequency of light.
E = hf
h = 6.63 x Js
The main postulate of quantum mechanical theory:
E is the smallest amount or quantum of energy (in joules) that can be transferred for a given wavelength of electromagnetic radiation.
Pg. 597 #2

18. The Photoelectric Effect
Einstein received the Nobel Prize in physics in 1921
Current flows if frequency of light is greater than threshold frequency (f0)
Work function, W, is the minimum amount of energy needed for the electrons to be emitted from metal surface.

19. Photons Light is made of particles called photons
Ephoton = hf
h = 6.63 x Js
1eV = 1.6 x J = 1V
Electron requires energy to escape surface of metal, left over energy provides Ek
Ek = hf - W
W = Work Function
Pg. 604 #11, 13, 14

20. What wavelength of light is required for ejecting photoelectrons from a tungsten surface (Wf = 4.52 eV) if the maximum kinetic energy of the electrons is 1.68 eV?
Light of frequency 8.0 x 1014 Hz illuminates a surface whose work function is 1.2 eV. What is the maximum speed with which an electron reaches the plate?
2.00 x 102 nm
6.3 x 105 m/s

21. 21. (a) Calculate the energy of a single microwave quantum of wavelength of 10.0 cm.
(b) Calculate how many quanta of 10.0-cm microwave energy would be required to raise the temperature of mL of water from 20°C to the boiling point, given that the specific heat capacity of water is 4.2 x103 J/kg?°C.
2 x 10-23J
4.2 x 1027

22. Applications Solar panels Photo-resistors Digital cameras
charge-coupled device (CCD) a semiconductor chip with an array of light-sensitive cells, used for converting light images into electrical signals

23. Textbook: pg 580 – 583 Homework: pg. 583 # 1 – 6
11.3 Mass and Energy: E = mc2
Textbook: pg 580 – 583
Homework: pg. 583 # 1 – 6

24. Relativistic Energy
Conservation of mass-energy

25. Calculate how much energy can be produced by the complete annihilation of 1.0 kg of mass.
Calculate the energy required to accelerate a proton from rest to 0.90c.
(mp = x10-27 kg)
9 x 1016J, x J

26. Probability versus Determinism
Textbook: 12.6
Homework: Read: pg 650 – 653

27. The de Broglie wavelength
The wave nature of matter is mathematically expressed by the de Broglie equation:
λ = wavelength (m
h = Planck’s constant (6.63 x Js)
m = mass (kg)
v = speed (m/s)

28. Momentum of a Photon: The Compton Effect
1923: American physicist A.H. Compton directed a beam of high energy X-ray photons at a thin metal foil
Compton effect: the scattering of lower – frequency photons by high-energy photons

29. Heisenberg’s Uncertainty Principle
If Δx is the uncertainty in a particle’s position, and Δp is the uncertainty in its momentum, then