IT’S PHYSICS
PHYSICS IS PHUN –NOVEMBER 2007
SWelcome and Thanks
SComment on origin of phrase “It’s Physics”
QHow does a magnifying glass work?
S“Use” magnifying glass like Sherlock Holmes
Use magnifying glass to start fire with sun’s rays
DL3-18 FOCUSING OF HEAT WAVES - OVERHEAD PROJECTOR
DL7-21 MAGNIFYING GLASS - TV
Comment: This is the “eyepiece” on a telescope or a microscope
QWhy does the pitch of a train whistle change as it passes you?
H1-52: AUDIOTAPE 82 MIN - SCIENCE OF SOUND - LONG VERSION
Section on Doppler Effect
Examples, Trains or gate clanging, beltway traffic
DH2-41 DOPPLER BALL
Rotate on string, the throw it
SFraunhofer spectrum
Comment: Doppler shift in stars gives their speeds to establish Expanding Universe
(page 2)
QWhy do you produce an electric spark when you shuffle across a rug and touch metal?
SQuantum mechanical tunneling effect
"Sea" of electrons
Actually CONTACT, not FRICTION - rubbing increases contact
STriboelectric series
DJ1-01 TRIBOELECTRICITY - CHARGING BY FRICTION
SVan de Graaff explanation
SAnother example of static electricity (charged babies)
CHARGING BY INDUCTION
DJ1-11 ELECTROPHORUS
SCharging by Induction
QWhat causes lightning?
Comment: Triboelectricity between air, water drops and ice crystals
SOrigin of lightning - general overview
SOrigin of lightning - various possibilities
SOrigin of lightning - image and discharge points
SOrigin of lightning - leader development
SOrigin of lightning - main stroke
SLightning striking tree - tree not damaged
SShoes of man struck by lightning - man not hurt, only scared
DJ2-03 VAN DE GRAAFF GENERATOR WITH GROUND SPHERE
DJ1-24 ELECTROSTATIC HAIR RAISING
DJ1-25 VAN DE GRAAFF - TRAINED RABBIT
Hare raising (ho, ho)
QHow does a lightning rod work?
DJ2-14 LIGHTNING ROD SIMULATOR
Lightning rod may not DRAW lightning, but PREVENT it.
(page 3)
QHow does a microwave oven work?
Two concepts:absorption of waves by conducting materials
microwave standing waves
SPolar molecule Applet
DJ4-12: ELECTROSTATIC FORCE - MOVING LUMBER
DG4-22 CHLADNI PLATES - OSCILLATOR DRIVEN
Story of Sophie Germain
SView of Microwave Oven
STemperature in various parts of oven
Myth: Microwave oven cooks “from the inside out”
Danger: It can cook you - or animal - if inside oven
DJ3-23: FARADAY CAGE - RADIOWAVES
SSuperheating video
QWhat are “Polaroid” sunglasses? How do they work
DK8-01 ELECTROMAGNETIC WAVE - MODEL
DM7-03 POLAROIDS AND GOOSENECK LAMP
DM7-17 REFLECTION OF LIGHT FROM DIELECTRIC AND CONDUCTOR
Comment: Light reflected from horizontal dielectric surface polarized horizontally
Examples: water, roads, especially wet roads
SExplanation
(page 4)
QWhat makes a rainbow?
DN1-01 PRISMATIC SPECTRUM OF WHITE LIGHT - POINT SOURCE
DN1-41 RAINBOW - RAY MODEL
DN1-44 RAINBOW - OPTICAL BOARD
“Mie Scattering”
Primary bow at 42 deg, blue inside and red outside
SPrimary rainbow, enhanced by use of polaroid filter
SDouble Rainbow
SDouble Rainbow #2
Secondary rainbow, 52 deg, red inside and blue outside
Comment: Glass bead angles 22 deg and 89 deg, due to greater refractive index
QWhy do stars “twinkle?’
DI2-43 CONVECTION - HOT PLATE
DE2-47 TWINKLING STAR
DE2-48 NON-TWINKLING PLANET
Stars are points, planets have relatively large size.
QWhy is the sky blue? Why is the sunset red?
SRe-phrase: Is the sky blue, or does it just look like it?
SRayleigh scattering
Blue light scattered more than red as it passes through the atmosphere.
DM7-31 TYNDALL'S EXPERIMENT - COLLOIDAL SUNSET
Sulfur particles get larger and more numerous with time
3SSlides of sunrise taken from airplane (while colloid is working)
STheEnd
PRE-SHOW DEMONSTRATIONS
J2-03 VAN DE GRAAFF GENERATOR WITH GROUND SPHERE
J1-24 ELECTROSTATIC HAIR RAISING
M7-17REFLECTION OF LIGHT FROM DIELECTRIC AND CONDUCTOR
J1-03 KILOVOLT CARPET
M7-05 ROPE AND COOKIE COOLERS
M7-03 POLAROIDS AND GOOSENECK LAMP
EXTRA POLAROID SQUARES
N1-43 RAINBOW - GLASS BEAD MODEL
F4-31 SIPHON
F4-32 SIPHON - CHAIN MODEL
L3-31 GIANT MIRROR - CONCAVE AND CONVEX
L3-32 CYLINDRICAL MIRROR DEMONSTRATOR
L3-03 LARGE CONVEX MIRROR
L3-14 LARGE CONCAVE MIRROR
L2-05 PERVERTED IMAGE - AXES IN MIRROR
B1-07 DOUBLE CONE - SMALL
B1-11 BALANCE MAN
B1-12 CENTER OF MASS - HINGED STICK PARADOX
B1-13 CENTER OF MASS - FORK AND SPOON ON TOOTHPICK
B1-14 CENTER OF MASS - BOTTLE
B1-15 TOPPLING CYLINDERS