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A single bubble in a liquid can be trapped in an acoustic field, which makes it expand and contract. The bubble will flash once every cycle when it reaches maximum compression. (Picture credit: K Suslick, UIUC)
A single bubble in a liquid can be trapped in an acoustic field, which makes it expand and contract. The bubble will flash once every cycle when it reaches maximum compression. (Picture credit: K Suslick, UIUC)