ELECtromagnetic waves

- Light etc.
- PHY 2054 Spring 2011
- April 13, 2011

Title

- Today we start the study of electromagnetic waves

and LIGHT as in let there be. - This will lead to a discussion of
- Polarization
- Mirrors
- Lenses
- Perhaps interference and diffraction
- There are available experiments for each of

these. Not sure how far we will get but we will

get there quickly!

April 2011 Time is on the move!

Sunday Monday Tuesday Wednesday Thursday Friday Saturday

1 2

3 4 Complete Induction 5 6 AC 7 8 AC Quiz? 9

10 11 COMPLETE AC EXPT 12 13 OPTICS EM Waves POLARIZATION 14 15 OPTICS Quiz 16

17 18 EXAM 3 (No Optics) 19 20 OPTICS 21 22 OPTICS 23

24 25 (LAST LASS) OPTICS 26 27 28 29 30 FINAL HPA 119 900 AM

WHERE IS THE FINAL EXAM??

Whats on Exam 3?

- Questions!
- 5 Multiple choice questions
- Three problems covering
- Magnetism
- Induction
- AC Circuits

A sound wave

- is a transverse wave
- is a longitudinal wave
- travels at the speed of light
- has a color spectrum

Sound Waves

Light

- James Clerk Maxwell (1831 - 1879) was a genius

who studied the properties of Electricity and

Magnetism. He took a mathematical approach. He

published his first scientific paper when he was

15 years old. - The four mathematical equations Maxwell produced

are ranked with Sir Isaac Newton's laws of motion

and Albert Einstein's theory of relativity as the

most fundamental contributions to (classical

)physics. - Maxwells equations predicted that the electric

field and the magnetic field could propagate

through empty space. - The calculated velocity of these waves turned out

to match the speed of light to a very close

precision. - It was later demonstrated that these waves were,

in fact, light waves.

Maxwells Equations

Gausss Law

No Mag Poles!!

Faradays Law

Amperes Law

Displacement Current

Which way is the electric field at P pointing?

A Left B Right C Up D Down E In/Out

? P

Electromagnetic Wave Generation

There is also a current here so there is one of

those B things.

Both Together

Propagation of Light

- The electric and magnetic fields are predicted

(and verified) to be perpendicular to each other. - The propagation velocity is found to be c, the

speed of light in a vacuum. - c3x108 m/sec.
- Maxwell calculated that the speed of light in a

vacuum to be

Propagation of Light

l

- Since the E and B fields (vectors) are

perpendicular to the direction of propagation,

the wave is said to be TANSVERSE. - Because of this fact, the light wave can be

polarized - The wavelength l of the wave is shown in the

diagram. - The product of the frequency and the wavelength

is c so we see that light can come in different

wavelengths (c is a constant)

Waving Along

Sir Isaac

The Electromagnetic Spectrum

Polarization

Polarization

Polarized Unpolarized

Changing It Around

Crossed Polarizer's can Transmit light!

Big Money!

Todays Experiment

- Polarized Light
- Read the material at the beginning of the

experiment that we havent covered - Dont read what we covered today
- Do the experiment
- Next time the math!

Get a Blue Box and get to work!!!

OPTICS STUFF