Interactions

What Happen When Light Runs into something? Transparent: Light goes right through and you can see what is on the other side Translucent: Light gets scattered because the material will transmit but don’t let the light travel through (stuff looks fuzzy)

Opaque: Light does not pass through, it gets reflected or absorbed Click for clip: build a house (so silly)build a house (so silly) Incase the other does not workhttp:// Video.php?video_id=27390&title=Build_ Me_an_Opaque_House&ref=Kathleenm arie63http:// Video.php?video_id=27390&title=Build_ Me_an_Opaque_House&ref=Kathleenm arie63

Ways Waves Interact Reflection Refraction Diffraction Interference Constructive Destructive Resonance

Reflection When an object or wave hits a surface through which it cannot pass, it bounces back. Not all waves reflect, light waves that reach eyeglasses transmit, meaning they pass through

Examples of reflection Mirror (light) Sun reflects off the moon (light) Echo (sound)

Refraction: A Definition A wave moves from one medium into another medium at an angle, it changes speed as it enters the second medium which causes it to bend. The bending of waves due to a change in speed is called refraction.

Refraction: An Example Though all waves change speed when they enter a new medium. Bending occurs when one side of the wave enters the new medium before the other side

So Why is the Sky Blue? Scattering: Light is sent in all directions – air will scatter short wavelenghts (roygbiv) more than long – as night falls, only the long wavelenghts are left, so the sky looks orange-ish

Cool….What’s this Called?

It’s Diffraction When a wave passes a barrier or moves through a hole in a barrier it bends and spreads out. Sound waves can be diffracted too. You can hear the music but can not see who is playing it…….why?

Because….. Light waves are much shorter than sound waves

Interference This is how 2 things can take up the same space at the same time. Matter can’t, but energy CAN! And waves are moving energy……

Interference Constructive interference occurs whenever two waves travel towards each other, combine to make a wave with a larger amplitude, then keep going in their own direction…watch

More Interference Destructive interference when the amplitudes of two waves combine producing a smaller amplitude, then go back from where they came….watch

Resonance Most objects have a natural frequency of vibration. Resonance occurs when vibrations traveling through an object match the object’s natural frequency. An object that is vibrating at its natural frequency absorbs energy from the objects that vibrate at the same frequency. Occurs in music. I’m tired of talking, Grandpa John will show you what I mean…

Introducing Grandpa John

Let’s Review Their Math is harder than mine …don’t let it scare you

The end