Demonstrating Science - Helium Bubbles
Watch David Richardson from the Institute of Physics demonstrate these fascinating, yet simple, physics experiments that you can replicate in class.
In this video he is demonstrating that helium is lighter than air with bubbles that rise.
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Step 1:
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Sinking Bubbles
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When you blow bubbles, you have probably noticed that they sink. This is partly to do with the fact that the air that we breathe out has got a large proportion of carbon dioxide, but also the mixture of the bubbles themselves is heavy and they will sink, so they tank when they go down
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Step 2:
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Helium Bubbles Rise
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If we do it with Helium though, what we should be able to demonstrate is that the gas which is lighter than air will rise up. You must not in front of the children inhale the helium because you are risk damaging yourself. We don't have to inhale the helium, instead we use a balloon attached to an ordinary laboratory hose and use that to blow bubbles.
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Step 3:
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The Experiment
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Can I have a volunteer, please? If you would like to hold the tube, I will fill up the balloon with helium. If you sqeeze the end of the tube, the gas doesn't come out and you can then use that to release the helium slowly by releasing the pressure between your fingers and then we can use that to blow the bubbles.
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Step 4:
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Sinking Feeling
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It gets around the problem of having to inhale the helium and demonstrates very nicely the density of the gasses and how helium is lighter than air. It rises compared to blowing where they definitely sink.
