Question

There are different soaps with different colours, but the colour of their froth is alway same. Why?

साबुन विभिन्न रंगों के होते हैं पर उन सभी के झाग का रंग समान होता है, क्यों?

Answer 1

When we wash our hands, apart from mixing soap with water, we also mix air. In its effort to avoid contact with air and in order to isolate it, the water creates bubbles, in other words foam. This explains the round shape of the bubbles. In addition the color of the foam always tends to be white, even in the case of colored soaps. This is due to the fact that bubbles store within them relatively more air than soap material. Besides, the color of the natural light is white. What we actually see is the reflection of the natural light in the bubble, which is white. However, if we for instance happen to be in a room with red lighting the foam might look reddish.