|Manila folder strips||48|
|Bowl (foam or paper)||24|
|Crayola Thick Markers||24|
|Cardboard (for the base)||24|
|Nails/Staples (demo: magnetism)||12|
|Batteries (handful for testing)||6|
|Soldering iron (PiE use only)||6|
|Electromagnets (demo: magnetism)||6|
|Wire spools (copper, 32-gauge, enameled)||2|
|Half-finished product (demo: EM to sound)||2|
|Finished product (demo: EM to sound)||2|
|Roll of sandpaper (for stripping)||1|
|Manila folder strips||2|
You’ve just built a speaker, so it’s important to know what sound is and how it works.
Sound is the compression and expansion of a medium like water or air. When you listen to someone talk or sing, its the person’s vocal cords that vibrate, manipulating the flow of air. The same occurs when an instrument is played. The instrument’s material, like a drum head, vibrates, compressing air. When the air gets to your ear, your ear has special equipment that allows it to translate the rate at which these compressed air molecules arrive. If the drum head is vibrating quickly/slowly, compressing the air at a quick/slow rate, it is associated with a high/low pitch.
EM to Sound
Finally! How does this all connect with each other? Let’s think about this like an engineer!
The electromagnet is taped to the bowl. When current flows through the electromagnet, it acts just like a regular magnet. As the electromagnet turns on, turns off, or switches direction, it is attracted or repelled to the magnet taped to the cardboard base. (When you use the speaker, can you see the oscillations?) This results in the oscillation of the bowl, the compression of air, and thus sound is made.