Download Class #28 Slides

3/29/06
Introduction to Waves & Sound
Questions about RHR
Questions about Faraday’s Law/Lenz’s Rule
No New Reading for Friday
Right Hand Rules Review
Direction of Magnetic FIELD
Direction of Magnetic FORCE
Another Example of Faraday’s Law & Lenz’s Rule: Eddy-Current Braking
A magnetic field points into the page as shown. For example, this field could be created by
an electromagnet or between the poles of permanent magnets. A metal pendulum swings
into the magnetic field. What happens to the motion of the metal pendulum? Why does
this happen?
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Poster Presentation: How Computers Work?
Date:
Monday May 1 (during lab time).
Work in Pairs
Moved from Monday April 23
Monitors
{
CRT
LCD
Plasma
Magnetic Hard
Drive/Memory
Optical Drives:
CD/DVD
{
{
Writing
Reading
Possible Topics?
Webcam/Digital Camera
Speaker/Microphone
Scanners
Printers: Laser/Inkjet
Read Only
Input Devices: Keyboard/Mouse
Recordable/
Rewritable
Lasers
Random Access Memory
(RAM): Dynamic/Static
Flash Memory
Wired Networks: Modems/Firewire/USB
Circuits/Processor: Diodes, Transistors
Wireless Networks
Power Supplies: AC  DC; Rechargeable Batteries
Exercise: Vibrations into Sound
1) Obtain Rubber Band
2) Hold rubber band in two hands,
slightly stretched
3) Pluck Rubber Band; Look & Listen
4) Stretch Rubber Band a little more;
Pluck; Look & Listen
5) Repeat Several Times
Questions: What is sound? How
does it connect to motion? How
does it connect to harmonic motion?
Exercise: Standing Waves, Wavelength,
Frequency, Wave Speed
1) Work in Pairs
2) Borrow long slinky
3) Follow Instructions
Questions: What are the various
standing wave patterns you saw?
What is relationship between
frequency and wavelength? What
happens if you change the length?