View source for Slinky Waves

{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Physics]]:
| Waves
|-
| Grade Range:
| [[Elementary School]], [[Middle School]], [[High School]]
|-
| Format:
| [[Hands-on]], [[Stage]]
|}

This is a great way to introduce the different types of waves to students. Be sure to either bring a volunteer to help, or to choose a good volunteer to help with this demonstration.

== Materials ==

* Slinky

== Safety Precautions ==

Please read the General Safety section of the [[Demonstration Safety]] page before performing this demonstration.

== Demonstration ==
;Presentation (Stage):
# Ask the audience to name different kinds of waves that they know of. After taking a few responses, state that there are three types of waves: Transverse, Compression, and Pressure waves. If you do not have a volunteer with you, choose a student to be a volunteer.
# Ask the audience to do "The Wave" with you. Starting at one end, ask the audience to lift their arms as you point at them, and move your arm from one side of the audience to the other and back again. After doing the wave, have your volunteer hold one end of the slinky so you can make a transverse wave, with an up-and-down motion.
# Next, call down 5-10 students to be volunteers, and have them stand spaced apart in a straight line in front of the audience. Have your volunteer stand at one end of the line, and place yourself at the other end.
# Turn and say "Hello" to the student next to you. When you do, bump shoulders with them, and have them pass the shoulder bump to the next student. have all the students pass the "message" down the line, bumping into each other, until the volunteer at the end is bumped. Have the volunteer now respond by saying "Hello" back and bumping the student next to them, and passing the bump back down the line until it reaches you. 
# Explain how this shows a compression wave, with the "up" motion being two students bumping into each other, and the "down" when they are separated. Have the students return to their seats, and then have your volunteer hold one end of the slinky so you can make a compression wave, with an in-and-out motion.
# State that a Surface wave is a combination of these two waves. Give examples of surface waves, like an ocean wave (water presses together, which creates the up-and-down motion we see) and seismic waves, or how earthquakes travel. Have your volunteer hold the end of the slinky so you can make a surface wave. The trick is to use both hands, and hold the end of the slinky and another part slightly down the slinky so you have slack. Make an up-and-down motion as you release the slack, while giving a slight in-and-out motion to help propel it. The motion seen should look like the slinky is "rolling". 
;Presentation (Hands-on):
# Ask a student to name a kind of wave. When they do, show them the way that wave travels using the slinky. Ask them to try and name other kinds of waves that show the other two types of waves.
# For older students, you can pass them the slinky and ask them to try to make the three types of waves with it. After they try to 30 seconds or so, take back the slinky and show them the types of waves they missed (if any) and what kinds of waves travel for each type.

== Why This Works ==

''Waves'' are a type of oscillation that accompanies a transfer of energy. The type of oscillation associated with the wave determines the type of wave it is. ''Transverse'' waves have an up-and-down motion, and most of them do not require a medium to pass through. Transverse waves travel best through vacuums, but they are easily blocked by solid matter. ''Compression'' waves have an in-and-out motion, and they require a medium to pass through. The more solid and rigid the medium, the better a compression wave can pass through it, but they are unable to pass through vacuums. ''Surface'' waves are a combination of the two listed above, with an up-and-down motion that accompanies the in-and-out motion. Surface waves travel best through liquids, and are the type of wave seen on water.
{| class="wikitable" style="color:black; background-color:#ddd; text-align: left; margin-right: auto"
|''' Type of Wave'''
|''' Motion of Wave'''
|''' Examples of Wave Type'''
|-
| '''Transverse''' or '''Sinosoidal''' Waves
| Up and Down
| Electromagnetic Waves, such as Light and Radio Waves
|-
| '''Compression''' or '''Longitudinal''' Waves
| In and Out
| Sound Waves, Seismic P-Waves
|-
| '''Surface''' Waves
| Up/Down and In/Out
| Waves on the Surface of Water, Seismic L-Waves
|}

== Additional Information ==

* This demonstration can be used as an optional introduction for the [[Flame Tube]]