Sound and Light

Sound and Light SoundSound is a mechanical wave that is vibrations transmitted through matter (solid, liquid, or gas)

The movement of the air molecules around a vibrating object is a sound wave

How does sound travel?Sound travels in wavesAs sound travels away from an object the waves become weaker

Bill Nye Waves video clip:http://www.youtube.com/watch?v=OGyRe_SGnck

Parts of a Sound WaveA CYCLE is the complete back & forth motion of a vibration

Lets build a sound WAVE!

What you will need:Yarn or stringScissorsGlueColored pencilsDirections: Use your yarn/string to make the shape of a sound wave and glue it on your paper. Label the following parts: amplitude, crest, trough, wave and cycle

Intensity and Volume of SoundIntensity is the strength of a sound (measured in decibels)

Volume is the loudness or softness of a sound

FYI: Sounds above 130 decibels can damage your ears!

PitchPitch is the frequency of a sound (measured in hertz)high frequency = high pitch (example: flute)Low Frequency = low pitch (example: tuba)

Sound and Matter

Sound cannot travel if there are no molecules of matter for it to travel throughSound causes particles of matter in air, liquid, or solids to vibrate and bump into another particlethink of it as the domino effectSound travels more quickly through substances with molecules that are closer togetherTry it outTry lining up dominoes close together and then farther apart.Which moves faster?

This simulates how sound moves through particles that are closer and farther apart.

Sound and TemperatureIn higher temperatures, sound moves more slowly since the air particles are farther apart

Try it outRules: no running and no shoving!Form two lines of people across the podOne line will have people an arms length away representing cooler air (cool air is more dense)The other line will have people 10 feet away from each other representing warmer air (warmer air is less dense)The goal: start at one end and touch the next person in line one by one until you get to the end. The line that gets to the end first winsThis shows how sound travels through matter of different temperaturesYou can calculate the distance of a storm!When you see a flash of lightening, count the number of seconds until you hear the thunderDivide the number of seconds by 5 seconds per mileThe answer will tell you how many miles away the storm is!It takes 6 seconds to hear thunder after a flash of lightening. How far away is the storm?6 seconds divided by 5 seconds per kilometerThe storm is 1.2 kilometers away!The purpose of this experiment is to watch lightning and hear thunder to give you clues about how far away you are from a storm.

Materials:One thunderstormA stop watch (or the ability to say "one-Mississippi")

After you see a flash of lightning, count the number of seconds until you hear the thunder. (Use the stop watch or count "One-Mississippi, Two-Mississippi, Three-Mississippi," etc.) 2. For every 5 seconds the storm is one mile away. Divide the number of seconds you count by 3 to get the number of miles.

You can calculate the distance of a storm!

http://soundbible.com/tags-thunder.htmlQuestions to Discuss1. What travels more quickly, light or sound? Why?

If you said light travels faster than sound, you're right! The lightning and thunder are happening at the same time, but light reaches you instantly, while sound takes longer.

2. Do you ever see lightning without hearing thunder? Why is that?

Some call that "heat lightning," but it is really lightning that is over 15 miles away and too far away for you to hear the thunder!

LOOK OUT if you see the lightning and hear the thunder at the same time!Sound is bouncy!Sounds can bounce off objectsIf a sound bounces back it is said to be reflectedSound that bounces back is called an echoEchos can be heard best when sound bounces off hard smooth surfaces

We can use echo sound to find object below the surface of waterthis is called sonar

We can use sound waves to see inside the human bodythis is called an ultrasound

Using Sound in Science

Let There Be Light!Light is a form of energy that can be seen

We see objects only because light is reflected off of them

Light is made of bundlesof energy called photons

Photons are tiny particlesa single photon is way too small to be seen

Light Waves

Like sound, light travels in wavesLight waves move like waves in water

Light waves travel FAST! 300,000 km per second!Parts of a Light Wave

CrestTroughVisible LightLight you see from the sun is white lightWhite light is made up of a band of colors called the Visible Spectrumyou can see these colors when you see a rainbow

You can use a prism see the colors in white light

Try It out!Make your own prism activityLight is Bouncy!Light bounces back or reflects when it hits an objectThe only reason we can see objects is because they reflect lightYou can see an image in a mirror because light waves are reflected

Different Types of MirrorsPlanea flat smooth surface

Concave this has a surface that curves inwardlike the inside of a spoon

Convex this has a surface that curves outwardlike the back of a spoonFor a demonstration visit: http://youtu.be/JBi3PWrsKlg

Plane Mirrors

This type of mirror gives the clearest image because the light reflects directly back

Concave MirrorsFYI: The focal point is the point where reflected light rays from concave mirror come together in front of the mirrorIf the image is located beyond the focal point of the mirror, it will appear upside down (inverted)If the object is in front of the focal point of the mirror, it will appear right side upIf the object is at the exact focal point it will not appear at all!

Convex Mirrors

This type of mirror creates an image that looks smaller than the real object

Though the image is smaller, you can see much more area in a convex mirrorthis is why convex mirrors are used a lot in store to help employees monitor retail areasHow is Light Bent?Refraction the bending of a wave as it moves from one material to another

Refraction Mini Lab!

Lens - a curved piece of clear material that refracts light waves

Concave Lens light that passes through this lens are spread apart

Convex Lens Light that passes through this lens is refracted inward (the human eye has a convex lens)

Take a moment to explore concave/convex lenses!

Lenses

Nearsighted and FarsightedNearsighted able only to see things clearly that are close up

Farsighted able only to see things clearly that are at a distance

Scattering Light Waves Lab!