Water rises in a capillary tube to a certain height such that the upward force due to surface tension is balanced by `75xx10^-4` newton force due to the weight of the liquid. If the surface tension of water is `6xx`10^-2` newton/metre the inner circumference of the capillary must be:

Options

A. `1.25 xx 10 ^(-2) m`
B. `0.50 xx 10 ^(-2)m`
C. `6.5 xx 10 ^(-2) m`
D. ` 12.5 xx 10 ^(-2) m`

Answer

A

Explanation

Weight of the liquid column `= T cos theta xx 2pi r.`
For water ` theta = 0^(@).` Here weight of liquid column
`W = 7.5 xx 10 ^(-4) N and T = 6 xx 10 ^(-2) N//m.`
Then circumference, `2pir =W//T =1.25 xx 10 ^(-2) m.`