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Q & A: The Dunking Bird

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Most recent answer: 10/22/2007
Q:
What other experiments follow the same principle as the "Dunking Bird" Experiment?
- Anonymous
A:
The Dunking Bird experiment works because the liquid in the bird separates two different areas of gas. Normally, these two areas have the same pressure. When you get the head of the bird wet this water will evaporate, which cools the gas in the head part of the bird, decreasing the pressure there. This "pulls" the liquid up into the head, which makes the bird tip over.

When it tips, two things happen: 1) the head gets wet again since it dips into a glass of water and 2) the liquid runs back into the bottom of the bird causing the bird to stand back up. The water on the head evaporates, and the whole cycle repeats.

A similar experiment is Franklin's Palm Glass (also called the Love Meter). The way this works is that you warm the liquid in the bottom of the tube in your hand. The liquid happens to be very volatile - this means that it evaporates very easily. Your hand is just warm enough to make the liquid in the bottom evaporate. When it does, it fills the bottom bulb with higher-pressure gas that pushes the liquid up into the top part.

Love meter with green liquid

Hope this helps!

-Tamara

(published on 10/22/2007)

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