Download it`s physics - Physics Learning Laboratories

IT’S PHYSICS
PHYSICS IS PHUN – NOVEMBER 2007
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Welcome and Thanks
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Comment on origin of phrase “It’s Physics”
Q
How does a magnifying glass work?
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“Use” magnifying glass like Sherlock Holmes
Use magnifying glass to start fire with sun’s rays
L3-18 FOCUSING OF HEAT WAVES - OVERHEAD PROJECTOR
L7-21 MAGNIFYING GLASS - TV
Comment: This is the “eyepiece” on a telescope or a microscope
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Q
Why 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
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H2-41 DOPPLER BALL
Rotate on string, the throw it
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Fraunhofer spectrum
Comment: Doppler shift in stars gives their speeds to establish Expanding
Universe
(page 2)
Q
Why do you produce an electric spark when you shuffle across a
rug and touch metal?
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Quantum mechanical tunneling effect
"Sea" of electrons
Actually CONTACT, not FRICTION - rubbing increases contact
Triboelectric series
J1-01 TRIBOELECTRICITY - CHARGING BY FRICTION
Van de Graaff explanation
Another example of static electricity (charged babies)
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CHARGING BY INDUCTION
J1-11 ELECTROPHORUS
Charging by Induction
Q
What causes lightning?
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Comment: Triboelectricity between air, water drops and ice crystals
Origin of lightning - general overview
Origin of lightning - various possibilities
Origin of lightning - image and discharge points
Origin of lightning - leader development
Origin of lightning - main stroke
Lightning striking tree - tree not damaged
Shoes of man struck by lightning - man not hurt, only scared
J2-03 VAN DE GRAAFF GENERATOR WITH GROUND SPHERE
J1-24 ELECTROSTATIC HAIR RAISING
J1-25 VAN DE GRAAFF - TRAINED RABBIT
Hare raising (ho, ho)
Q
How does a lightning rod work?
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J2-14 LIGHTNING ROD SIMULATOR
Lightning rod may not DRAW lightning, but PREVENT it.
(page 3)
Q
How does a microwave oven work?
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Two concepts: absorption of waves by conducting materials
microwave standing waves
Polar molecule Applet
J4-12: ELECTROSTATIC FORCE - MOVING LUMBER
G4-22 CHLADNI PLATES - OSCILLATOR DRIVEN
Story of Sophie Germain
View of Microwave Oven
Temperature in various parts of oven
Myth: Microwave oven cooks “from the inside out”
Danger: It can cook you - or animal - if inside oven
J3-23: FARADAY CAGE - RADIOWAVES
Superheating video
Q
What are “Polaroid” sunglasses? How do they work
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K8-01 ELECTROMAGNETIC WAVE - MODEL
M7-03 POLAROIDS AND GOOSENECK LAMP
M7-17 REFLECTION OF LIGHT FROM DIELECTRIC AND CONDUCTOR
Comment: Light reflected from horizontal dielectric surface polarized horizontally
Examples: water, roads, especially wet roads
Explanation
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(page 4)
Q
What makes a rainbow?
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N1-01 PRISMATIC SPECTRUM OF WHITE LIGHT - POINT SOURCE
N1-41 RAINBOW - RAY MODEL
N1-44 RAINBOW - OPTICAL BOARD
“Mie Scattering”
Primary bow at 42 deg, blue inside and red outside
Primary rainbow, enhanced by use of polaroid filter
Double Rainbow
Double 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
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Q
Why do stars “twinkle?’
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I2-43 CONVECTION - HOT PLATE
E2-47 TWINKLING STAR
E2-48 NON-TWINKLING PLANET
Stars are points, planets have relatively large size.
Q
Why is the sky blue? Why is the sunset red?
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Re-phrase: Is the sky blue, or does it just look like it?
Rayleigh scattering
Blue light scattered more than red as it passes through the atmosphere.
M7-31 TYNDALL'S EXPERIMENT - COLLOIDAL SUNSET
Sulfur particles get larger and more numerous with time
Slides of sunrise taken from airplane (while colloid is working)
TheEnd
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PRE-SHOW DEMONSTRATIONS
J2-03 VAN DE GRAAFF GENERATOR WITH GROUND SPHERE
J1-24 ELECTROSTATIC HAIR RAISING
M7-17 REFLECTION 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