Question

Hair of shaving brush clings together when it is taken out of the water due to

• A. the force of attraction between the hair
• B. surface tension
• C. viscosity of water
• D. characteristic property of hair

Answer 1

The correct option is B

surface tension

Hair of shaving brush clings together when it is taken out of the water. When the shaving brush is inside the water, its hair does not cling together, so, it is not exactly the wetness of the brush that makes the hair clings together. When the brush is inside the water, there is water all around its hair. Consequently, there is no free surface and the effect of surface tension is absent. However, when the brush is taken out of the water, the force of surface tension contracts the hair making it cling together.