Question

If $R$ is radius of meniscus of liquid in capillary and $r$ is radius of capillary tube.

The angle of contact will be :

• A. ${\cos }^{-1}\left(\frac{r}{R}\right)$
• B. ${\cos }^{-1}\left(\frac{R}{r}\right)$
• C. ${\cos }^{-1}\left(rR\right)$
• D. ${\cos }^{-1}\left(R\right)$

Answer 1

The correct option is A ${\cos }^{-1}\left(\frac{r}{R}\right)$

We all know that

$\theta ={\cos }^{-1}\left(\frac{r}{R}\right)$

Answer: $\left(A\right){\cos }^{-1}\left(\frac{r}{R}\right)$