Question

In a U-tube the radii of two columns are respectively r₁ and r₂. When a liquid of density r (q = 0ŗ) is filled in it, a level difference of h is observed on two arms, then the surface tension of the liquid is –

• A. $\frac{\rho ghr_{1}r_{2}}{2(r_{2}–r_{1})}$
• B. hrg (r₂– r₁)
• C. $\frac{h\rho g(r_{2}–r_{1})}{2}$
• D. $\frac{h\rho g}{2(r_{2}–r_{1})}$

Answer 1

Answer: (A)

$\frac{\rho ghr_{1}r_{2}}{2(r_{2}–r_{1})}$

Answer 2

rgh = 2T $\left( \frac{1}{r_{1}}–\frac{1}{r_{2}} \right)$ = 2T $\left( \frac{r_{2}–r_{l}}{r_{1}r_{2}} \right)$

\ T = $\frac{\rho ghr_{1}r_{2}}{2(r_{2}–r_{1})}$