The area of cross -section one limb of an U- tube is twice that of other . Both the limbs contain mercury at the same level . Water is poured in the wider tube so that mercury level in it goes down by 1 cm . The height of water column is (density of water `=10^(3)kgm^(-3)`, , density of mercury `=13.6xx10^(3)kgm^(-3))`

Options

A. `13.6m`
B. `40.8m`
C. `27.2m`
D. `54.4m`

Answer

B

Explanation

The depression of level in the left limb is 1 cm , so the rise of level of mercuri in right limb be 2 cm , because the area of cross -section of left limb is twice as that of right limb .

Now , equating pressure at interface of mercury and water (at A.B.)
`(x+1)xx10^(3)xxg=(1+2)xx13.6xx10^(3)`g
or height of water column
`x+1=40.8 m`