Question

A capillary tube of radius r is dipped inside a large vessel of water. The mass of water raised above water level is M. If the radius of capillary is doubled, the mass of water inside capillary will be

• A. 5M
• B. 2M
• C. $\frac M4$
• D. M

Answer 1

Answer: (B)

2M

Answer 2

Mass of water in capillary rise $= Ahρ$
Where,
$A$ = area of cross-section,
$h$ = height,
$ρ$ = density

$⇒ m = (\pi r^2 )hρ$

$⇒ m = (\pi r^2 ).\frac {2σ\ cos \theta}{rρg}$

$⇒m∝r$
If radious is doubled then mass will also get doubled.
$⇒m’ =2M$

So, the correct option is (B): 2M