The Gold Medal Appears and Disappears

Let's take a look!

What type of experiment is this?

Experimental procedure and explanation:

• Pour water into the cup, and a gold medal will appear.
• Add more water to get a better view, then the gold medal disappears.
• The initial appearance of the gold medal is explained by the same principle as in the “Mysterious Bowl” experiment.
• When more water is added, the gold medal disappears because water starts to leak out due to the siphon effect. This is the same principle demonstrated in the “Disappearing Juice” experiment.
• When the water level in the cup is below the bend in the straw, nothing unusual happens. As the water level rises above the bend, water begins to flow out through the straw (siphon principle). Once the flow starts, all the water inside drains out, causing the gold medal to disappear.
• This video was produced with the support of the JSPS Grant-in-Aid for Scientific Research (18K03956).

[Keywords]	Refraction of light, siphon principle
[Related items]	Mysterious Bowl, Disappearing Juice

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