Water rises in a capillary tube upto a height h so that the upward force due to surface tension is balanced by the force due to the weight of the water column. If this force is `75xx10^-5N` and surface tension of water is `6xx10^-2N/m`. Then what is the inner circumference of the capillarity?

Explanation

Upward force due to ST = weight of the lifted liquid
`therefore T = F/l `therefore` upward force `F = T xx L = T xx 2pir`
`therefore T xx 2pir = mg`
inner circumference of the capillary
= `2pir = (mg)/T = (90 xx 10^-5)/(6 xx 10^-2)` [`because 1N = 10^5` dyne]
`15 xx 10^-3 = 1.5 xx 10^-2 m`