Question

A very narrow capillary tube records a rise of 20 cm when dipped in water. When the area of cross section is reduced to one fourth of the former value, water will rise to a height of-

• A. 10 cm
• B. 20 cm
• C. 40 cm
• D. 80 cm

Answer 1

Answer: (C)

40 cm

Answer 2

A become A/4 so radius become just half of its present value and h µ $\frac{1}{r}$ so h become just double so h = 40 cm.