Question

A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator, then the length of the water column in the capillary tube will be:   

Options

• 8 cm

• 6 cm

• 10 cm 

• 20 cm

Answer 1

20 cm

Explanation:

The apparent weight of the water column in a freely descending elevator is zero. Thus, water fills the entire length of the capillary tube before its curvature is adjusted (becomes flat), resulting in the elimination of the surface tension's net pull on the liquid column.