1.

Water rises to a height of 10 cm in a capillary tube and mercury falls to a depth of 3.42 cm in the same capillary tube. If the contact angle for mercury and surface tension of water and mercury is

Answer»

`1:0.15`
`1:3`
`1:6.5`
`1.5 : 1`

SOLUTION :As, height raised `H=(2S cos theta)/(r RHO g)`
or `S=(hr rho g)/(2 cos theta) implies S prop (h rho)/(cos theta)`
`:. S_(w)/S_(Hg)=h_(1)/h_(2)XX(cos theta_(2))/(cos theta_(1))xxrho_(1)/rho_(2)`
`=10/((-3.42))xx(cos 135^(@))/(cos 0^(@))xx1/13.6`
`S_(w)/S_(Hg)=10/3.42xx0.707/13.6=1/6.5`


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