All Things Beautiful: Light and Sound

Showing posts with label Light and Sound. Show all posts

What Things Affect Sound?

We performed a series of sound experiments. First I took a board (6 inches by 18 inches, 1 inch thick), several weights of fishing line and 3 2-liter bottles ( you could use 1/2 gallon plastic milk jugs) and 3 screw eyes (size 14). Screw one screw eye in the middle of one end of the board. Screw in one of the other screw eyes on either side. This is the set up for all three experiments.

How does thickness affect a line's sound?

In the first experiment, tie 3 feet of 50pound test weight fishing line to the first screw eye. Tie 3 feet of 30 pound test weight fishing line to the middle screw eye and 8 pound test weight fishing line to the last screw eye. Tie the other end of the fishing lines to the bottles. Fill each of the bottles with 2 cups of water. Position the board so that the end opposite the screw eyes is even with the end of the table. Let the bottles hang over the edge of the table.

Pluck each line and compare the sounds.

The heavier the weight of the line, the lower the sound will be because it has more weight to move and therefore is slower. Slower vibrations equal lower sounds.

How does tension affect a line's sound?

For the second experiment, remove the 30 and 8 pound weight pieces of fishing line and replace them with two more 3-foot pieces of 50 pound weight line. Tie lines to the bottles as before but this time, leave one with the 2 cups of water, but add 1 more cup to one (for a total of 3 cups ) and 3 more cups to the last one (for a total of 5 cups). Arrange as before, with the bottles hanging over the edge of the table. Pluck each line. Do they sound different?

Increasing the weight stretches the line tighter, increasing the tension. A tighter string springs back faster to its original position, producing a higher pitch (and frequency).

How does length affect a line's sound?For the last experiment, you can keep the setup the same as the last experiment. You just press one of the strings down with one finger, and pluck with the other. Press the string down at a different point, and pluck it again. How does the sound change?
The shorter the length of the string, the higher the sound results. Because the vibrations have to travel through the string to produce the sound, the longer the string, the longer it has to travel. This longer traveling, slows down the vibrations and lowers the pitch.

So what did we learn?

How thick a line is, how tightly it is stretched and how long the line is are all factors that affect sound. We will be using this information when we build our own musical instruments.

More neat sound experiments:

Observing Sound Vibrations

Playing with Sound

More Fun with Sounds

Egg carton and Wrench Xylophone

Seeing Sound

Another Experiment for Seeing Sound
About Sound and Irish Harps

Sound Explorations

Quentin had gotten this set of water flutes for Christmas. The boys had played with them in the bath, but I got them out today and we used the cards that came with it to play some songs such as Old MacDonald had a Farm. The flutes play different notes depending on how much water is put in them.We talked about how the highness or lowness of a sound is called Pitch. They are so cool! I highly recommend them as a toy.

Have you ever made sounds with a glass and some water? Moisten a finger with water and rub it evenly around the top of a glass to make a ringing sound.

Ben Franklin designed a version of this called the glass harmonica. This instrument had a row of glass bowls mounted on a long axle attached to a wheel. The lower half of the bowls rested in water. The player used the fingers of both hands to rub the wet glasses as they turned.

We also talked about how air is not the best conductor for sound. Sound actually travels much more quickly through solids. I rapped on the table and they listened and then I asked them to put their ear to the table and I rapped on the table with the same volume and they immediately could see that the sound waves traveled much more quickly and thoroughly through the table. Speaking of sound as vibrations, this is easily demonstrated by having your kids whisper and put their fingers on their throats and feel for the vibrations. Then have them shout and feel for the vibrations. Now have them sing with high notes and low notes. Low sounds are caused by slow vibrations, which can be easily felt, and high sounds are made by faster, smaller movements that are harder to feel.
Sound and light move in wave patterns. Have a student hold one end of the rope and you take the other end and raise your arm up and then bring it down, creating a wave.

Then have them lay out a rope, in a wave pattern they saw when they were moving the rope, on a table for students to sketch...

and you can teach them the vocabulary about sound and light waves to add to their sketches.
Music and pleasurable sounds such as bells and birds chirping create regular sound wave patterns such as this.
Difference Between Music and Noise (musical sound wave) | The Happy Housewife

Difference Between Music and Noise (musical sound wave) | The Happy Housewife

Noises such as doors closing, traffic, or blenders make erratic wave patterns like this.
Difference Between Music and Noise (noise sound wave) | The Happy Housewife

Difference Between Music and Noise (noise sound wave) | The Happy Housewife

Resources:

You can make your own set of flutes with jars and water. Plot 55 has a wonderful demonstration on how to make the notes by color..

sources:

Difference Between Music and Noise at The Happy Housewife

Learning about Lenses

The first thing I did was open my pouch and leave out the materials for a couple of days. Quentin asked what all the glass was for. I told him that he would see, but if he wanted to look at them meanwhile he could if he was extra careful with them.