Water rises to a height of `10cm` in a glass capillary tube. If the area of cross section of the tube is reduced to one fourth of the former value what is the height of water rise now?

Options

A. 5 cm
B. 10 cm
C. 20 cm
D. 2 cm

Answer

C

Explanation

`h_(1) = 10 cm , A_(2)= 1/4 A _(1) , h_(2) = ? `
`A_(2) = 1/4 A_(1)`
` pi r_(2)^(2)=1 /4 pi r_(1)^(2)`
` r_(2) = (r_(1))/2`
`h_(2)r_(2)=h_(1)r_(1)`
`h_(2) = (h_(1)r_(1))/(r_(2)) = 10 xx r_(1)/(r_(1)/2)= 20`
` h_(2) = 20 cm`