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ITS PHYSICS

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ITS PHYSICS

    IT’S PHYSICS

    PHYSICS IS PHUN NOVEMBER 2007

S Welcome and Thanks

S Comment on origin of phrase “It’s Physics”

Q How does a magnifying glass work?

    S “Use” magnifying glass like Sherlock Holmes

     Use magnifying glass to start fire with sun’s rays

    D L3-18 FOCUSING OF HEAT WAVES - OVERHEAD PROJECTOR D L7-21 MAGNIFYING GLASS - TV

     Comment: This is the “eyepiece” on a telescope or a microscope

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 D H2-41 DOPPLER BALL

     Rotate on string, the throw it

    S 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?

    S Quantum mechanical tunneling effect

     "Sea" of electrons

     Actually CONTACT, not FRICTION - rubbing increases contact S Triboelectric series

    D J1-01 TRIBOELECTRICITY - CHARGING BY FRICTION S Van de Graaff explanation

    S Another example of static electricity (charged babies)

     CHARGING BY INDUCTION

    D J1-11 ELECTROPHORUS

    S Charging by Induction

Q What causes lightning?

     Comment: Triboelectricity between air, water drops and ice crystals

    S Origin of lightning - general overview

    S Origin of lightning - various possibilities S Origin of lightning - image and discharge points S Origin of lightning - leader development

    S Origin of lightning - main stroke

    S Lightning striking tree - tree not damaged S Shoes of man struck by lightning - man not hurt, only scared D J2-03 VAN DE GRAAFF GENERATOR WITH GROUND SPHERE D J1-24 ELECTROSTATIC HAIR RAISING

    D J1-25 VAN DE GRAAFF - TRAINED RABBIT

     Hare raising (ho, ho)

Q How does a lightning rod work?

    D J2-14 LIGHTNING ROD SIMULATOR

     Lightning rod may not DRAW lightning, but PREVENT it.

    (page 3)

Q How does a microwave oven work?

     Two concepts: absorption of waves by conducting materials

     microwave standing waves

    S Polar molecule Applet

    D J4-12: ELECTROSTATIC FORCE - MOVING LUMBER D G4-22 CHLADNI PLATES - OSCILLATOR DRIVEN

     Story of Sophie Germain

    S View of Microwave Oven

    S Temperature in various parts of oven

     Myth: Microwave oven cooks “from the inside out”

     Danger: It can cook you - or animal - if inside oven D J3-23: FARADAY CAGE - RADIOWAVES

    S Superheating video

Q What are “Polaroid” sunglasses? How do they work

    D K8-01 ELECTROMAGNETIC WAVE - MODEL

    D M7-03 POLAROIDS AND GOOSENECK LAMP

    D M7-17 REFLECTION OF LIGHT FROM DIELECTRIC AND CONDUCTOR

     Comment: Light reflected from horizontal dielectric surface polarized horizontally

     Examples: water, roads, especially wet roads S Explanation

    (page 4)

Q What makes a rainbow?

    D N1-01 PRISMATIC SPECTRUM OF WHITE LIGHT - POINT SOURCE D N1-41 RAINBOW - RAY MODEL

    D N1-44 RAINBOW - OPTICAL BOARD

     “Mie Scattering”

     Primary bow at 42 deg, blue inside and red outside S Primary rainbow, enhanced by use of polaroid filter S Double Rainbow

    S 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

Q Why do stars “twinkle?’

    D I2-43 CONVECTION - HOT PLATE

    D E2-47 TWINKLING STAR

    D E2-48 NON-TWINKLING PLANET

     Stars are points, planets have relatively large size.

    Q Why is the sky blue? Why is the sunset red? S Re-phrase: Is the sky blue, or does it just look like it? S Rayleigh scattering

     Blue light scattered more than red as it passes through the atmosphere.

    D M7-31 TYNDALL'S EXPERIMENT - COLLOIDAL SUNSET

     Sulfur particles get larger and more numerous with time 3S Slides of sunrise taken from airplane (while colloid is working) S TheEnd

    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

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