The radius of capillary tube is 1.4mm. Water of height due to force `6.28xx10^-4N` rise in the capillary tube, when it is vertically dipped in water. What is the surface tension of water?

Explanation

The upward force due to
ST = `2pir xx T` [because` T = F/l]`
and the down ward force = weight of the lifted water.
`therefore T xx 2pir = 6.28 xx 10^-4`
`therefore T = (6.28 xx 10^-4)/(2 xx 3.14 xx 1.4 xx 10^-3) = (10^-1)/1.4 = 7 xx 10^-2 N/m`