Why are bubbles round or more specifically spherical?
? A soapy bubble’s walls are sort of like layers of a sandwich with an ultra-thin layer of soap on the outside & the inside surrounding an ultra-thin layer of water in the middle.
? When you blow on soapy water, the ultra-thin soap & water film traps air & holds it inside by a force called
? The air molecules that are trapped inside the layer, push outwards against the water.
? Simultaneously the air molecules on the outside push inwards (exerting an equal and opposite force).
? Bubbles are spherical because the shape can contain the largest contents within the smallest circumference.
(The geometric form with the lest surface area for any given volume is a sphere.)
Why are soap bubbles rainbow so colourful?
? The colours of a soap bubble come from white light, which contains all the colours of the rainbow.
? When white light from the sun shines through the film of the bubbles, the light is reflected and dispersed, splitting white light into its different wave lengths revealing all the colours of the rainbow!
? Infact, once when Isaac Newton was bathing, he discovered that you could calculate the size of the soap molecule just by following the colours of the bubble!
(If you observe closely, you will notice that the colours of the bubbles gradually change as the water film drains under gravity.)
POP goes the bubble!
? If a bubble touches a dry finger, it pops because the water molecules are attracted to your dry skin. The bubbles last as long as the water does, so if the surface tension is disturbed, POP it goes!
? To delay this, try wetting your hands first.
☀️ Sometimes, this phenomenon can happen without touching because the water in the bubble gradually evaporates, making the film weaker, casing it to POP!