Films
المؤلف:
GEORGE A. HOADLEY
المصدر:
ESSENTIALS OF PHYSICS
الجزء والصفحة:
p-122
2025-11-08
43
If we make the thickness of the liquid mass very little, and give to it two free surfaces, surface tension may be studied to better advantage.
Demonstrations. - Make a strong solution of soap by dissolving castile soap in water until a large bubble can be blown. Bend a piece of iron wire so as to form an open frame with a handle, and from one side of the frame hang a loop L made of one strand of a silk thread. Dip this frame in the soap solution, and the loop will hang as at A in Fig. 1. Remove the film within the loop by touching it with the point of a piece of blotting paper, and the loop will at once spring out into the form of a circle, as at B.
Using a clay pipe or a glass tube, blow a small-sized bubble. Remove the tube from the mouth, and hold the end of it toward the flame of a lighted candle. The pressure exerted by the surface tension of both sides of the film will force out a current of air strong enough to blow the flame to one side.
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