Workshop for High School Physics Teachers

American Physical Society meeting
Westin Hotel Indianapolis, March 19, 2002

Mike Moloney, Elaine and Scott Kirkpatrick, and Albert McGarvey

• Sample Excel Spreadsheets and Discussion
• Experiment to Determine the Wavelength of white light using a cloth grating
• Hearing 'chimes' from coathangers and other wires
• A falling magnet lights red and/or green LEDs as it passes
• magnet slides down a 1/2" pvc pipe
• the LEDs are connected across a coil around the pvc pipe
• when the magnet goes fast enough there is enough emf to light one or more LEDs
• the red LED needs a lower voltage than the green, so just the right speed lights the red but not the green LED
• list of manufacturers of the magnets and coils we used
• Making squawkers (cup and string, soda straws)
• a hole is made in the botttom of a plastic cup
• a string is put through the hole and knotted
• by pulling or scraping on the string, one makes a squawk
• or,
• one cuts the end of a soda straw into a 'V' shape
• the ends of the 'V' are supposed to be slender, and vibrate like a reed
• one blows through the 'V' and makes a sound
• as this sound is being made, one cuts off the straw shorter and shorter
• the frequency goes up as this happens, due to the shorter length
• Jello Optics
• one makes a shallow pan of jello (instructions)
• one cuts the jello into shapes and passes light from a laser pointer through the shapes
• cut a strip 1-2" wide to act as a waveguide.
• Place on a surface like transparency plastic on stiff cardboard
• send light from a laser pointer into the strip
• vary the angle and observe total internal reflection
• gently bend the strip and observe the light 'follow' the curve
• bend the strip more, and observe light losses near the bend
• cut a plano-convex lens from the pan and place on a separate surface
• use a flashlight to shine light into the 'lens' and observe focusing
• Place crossed polaroid across the width of a strip of jello
• Press gently on the jello and observe the effects of this stress using the crossed polaroids