When one end of the capillary is dipped in water, the height of water column is `'h'`. The upward force of 105 dyne due to surface tension is balanced by the force due to the weight of water column . The inner circumference of the capillary is
(Surface tension of water `= 7 xx 10^(-2) N//m`)

Options

A. 1.5 cm
B. 2 cm
C. 2.5 cm
D. 3 cm

Answer

A

Explanation

Given, `F = 105` dyne, `= 105 xx 10^(-5) N`
`T = 7 xx 10^(-2) N//m`
As we know, circumference of the capillary x surface tension = upward force
`2pirt = F`
`2pir = (F)/(T) = (105 xx 10^(-5))/(7 xx 10^(-2)) = 15 xx 10^(-3) m`
`= 1.5 xx 10^(-2) m = 1.5` cm