Stethoscope Experiment

Check Your Heart Rate
What you'll need:

• A balloon
• A piece of tubing
• 2 small funnels
• Scissors
• A timer
• Rubber band (optional)
• A calculator (optional)

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Instructions:

1. Take the piece of tubing and fit a funnel to each end.
2. Stretch the balloon by blowing it up and then letting the air out.
3. Cut off the top third of the balloon with scissors.
4. Stretch the top third of the balloon tightly over the open end of one the funnels. If necessary, use a rubber band to hold it in place.

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The Science Behind It: 
Like an eardrum in your ear the ballon amplifies the sound vibrations. The sound waves traveling through the stethoscope are having ther amplitude increased which allows us to hear it.

Source: http://www.sciencekids.co.nz/projects/stethoscope.html