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Science experiment: Sound Waves

Ever wonder about sound and how it travels? Here we are working on a really really super simple but awesome Science experiment about the sound waves. As you can’t really see how it works, you get to hear and feel how it works. In some schools, they call this the invisible Science experiment. Now let’s get started!

What you need (Don’t panic! I’m sure you can easily find these items around the house):
– a hanger
– a string
– chopstick or pencil (optional)
– mini speaker (optional)
– mobile phone (optional)
– empty bowls or cups with paper to cover the openings (optional)
– beans or pasta or mini objects to be placed on the bowls or cups (optional)

What you need to do:
1. Tie the string on the hanger’s hook. Make sure is tight and the hanger is hanging in the center when you hold both ends of the strings up.
2. Take each end of the string and wrap them around your child’s finger on each hand. Then push the string against each ear (NOT INTO the ear but just outside).

Ok, now get ready…

3. You GENTLY (take note is GENTLY) hit the hanger with a chopstick or a pencil
4. QUICKLY, watch the look on your child’s face!

I did the experiment with mei mei and her expression was priceless! Too bad, I missed the “ah ha” moment on her face when I first hit the hanger. She looked so amazed how the sound travels through the string to her ears and she requested me to try hitting it a few more times. I tried with different strength and she would tell me how it sounds. Sometimes she would say it sounds like a small bell or a big church bell, at times like a drum. She got excited and began to hit the hanger on the furniture around her to check out the effect.

What’s going on:
When you hit the hanger, it creates sound waves. Sound waves are created by the vibration of an object. These vibrations move up through the objects and to your ears. Your brain will then interprets these vibrations as sound. Sound waves travel through liquid, solid and air. In our experiment, the sound waves are traveling through solid. As sound waves travel more quickly though solid, we get to hear the sound more clearly.

To test sound waves through air, we used the speaker and the mobile phone.

To see the vibrations, we placed the bowl (as shown in the above picture) on top of the speaker. Once we turned on the speaker, we can see that the beans and the pasta started “dancing”. It was truly a fascinating scene, especially for mei mei.

What are the properties of sound:
Volume – loud and soft
Pitch – high and low
Frequency – how fast a sound wave moves (high frequency = short wavelength = high pitch)

Interesting fact:
As sound waves travel slower than light waves, that explains why during a thunderstorm you see the lightning first before hearing the thunder. In actual fact, they happened at the same time. Pretty cool, isn’t it?

Alrighty, that’s all for sound waves experiment today. Do stay tuned for more Science experiments in our next blog posts. Meanwhile, check out this awesome video that explains how sound works.

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