Question

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

Answer 1

Correct Answer - C
`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`