Your voice is a vibration, and you can feel it when you place a hand on your throat when you speak. As long as there are molecules around, sound will be traveling though them by smacking into each other.
That’s why if you put an alarm clock inside a glass jar and remove the air, there’s no sound from the clock. There’s nothing to transfer the vibrational energy to – nothing to smack into to transfer the sound. It’s like trying to grab hold of fog – there’s nothing to hold on to.
[am4show have=’p8;p9;p16;p43;p151;p64;p75;p100;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Here’s what you need:
- two tongue depressors
- three rubber bands, one at least 1/4″ wide
- paper
- tape
Download Student Worksheet & Exercises
What’s going on? The rubber band vibrates as you blow across the rubber band and you get a great sound. You can change the pitch by sliding the cuffs (this does take practice).
Troubleshooting: This project is really a variation on the Buzzing Hornets, but instead of using wind to vibrate the string, you use your breath. The rubber band still vibrates, and you can change the vibration (pitch) by moving the cuffs closer together or further apart. If the cuffs don’t slide easily, just loosen the rubber bands on the ends. You can also make additional harmonicas with different sizes of rubber bands, or even stack three harmonicas on top of each other to get unusual sounds.
If you can’t get a sound, you may have clamped down too hard on the ends. Release some of the pressure by untwisting the rubber bands on the ends and try again. Also – this one doesn’t work well if you spit too much – wet surfaces keep the rubber band from vibrating.
Exercises
- What is sound?
- What is energy?
- What is moving to make sound energy?
[/am4show]
i’m a kinesthetic learner and i love this program!!!!
Yes, they aren’t nearly as thick, so you’ll have to blow harder for the vibrations to sound right.
will popsicle sticks work
Sound waves do increase the temperature of the medium they travel through if they are absorbed by the medium. For example, therapeutic ultrasound uses this to heat-up skin tissues. From a loud speaker, you wouldn’t get any noticeable increase in temperature.
So if sound is vibrating particles and heat is increased motion of particles why don’t I heat up in front of a speaker? Is there an increase in temperature where the sound waves travel?
I made the harmonica, and my sister loved it.We had to make something and explain how to do it in Spanish, and she did it.
-Vela
Good question Finn! Particles can be attracted to each other, like the north and south pole of a magnet, or repel each other, like the south and south poles of a magnet, or be neutrally charged, like most things (a chair, a table, etc.) Air is usually neutrally charged, meaning that it’s doesn’t have a preference one way or the other. If you charge up the air (called ionizing) then the air will move one way or the other, depending on the charge of the object near by. And when air molecules crash, they really just bounce off each other like bouncy-balls, not like a car crash that leaves both cars wrecked and not looking like cars at all after the impact. Does that help?
Why do air particles crash into each other instead of move away from each other so they won’t crash? Finn, 5 years old.
Try a tongue-depressor size stick, like doctor’s use to look down your throat. 🙂
i do not know how to make it
dose it need to be a big stick or a small stick
samuel ;] ;/ ;[
It’s usually because the paper didn’t lift the rubber band off the stick high enough. Try changing the spacing between the cuffs and see if this helps.
Boohoo my harmonica dosn’t work! 🙂 Mabey its because I used plain plosicle sticks.
It’s nice to make a harmonica when you don’t have a real one. 🙂
This harmonica didn’t work for me.
Whoops – I’ll have our web guy upload a new version right away. Sorry about that! 🙂
Hi Aurora,
We don’t have sound with this video……any ideas?
thanks,
Michelle