1. 3/29/06 Introduction to Waves & Sound Questions about RHR Questions about Faraday’s Law/Lenz’s Rule No New Reading for Friday

2. Right Hand Rules Review Direction of Magnetic FIELD Direction of Magnetic FORCE

3. 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? x x x

4. Poster Presentation: How Computers Work? Date: Monday May 1 (during lab time). Work in Pairs Moved from Monday April 23 Possible Topics? Monitors { CRT LCD Plasma Magnetic Hard Drive/Memory { Writing Reading Optical Drives: CD/DVD { Read Only Recordable/ Rewritable Input Devices: Keyboard/Mouse Webcam/Digital Camera Speaker/Microphone Printers: Laser/Inkjet Scanners Circuits/Processor: Diodes, Transistors Random Access Memory (RAM): Dynamic/Static Flash Memory Lasers Power Supplies: AC  DC; Rechargeable Batteries Wired Networks: Modems/Firewire/USB Wireless Networks

5. 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?