Question

A metal wire of density $d$ floats, in a liquid of surface tension $\sigma,$ in the horizontal position. The maximum radius of the wire so that it may not sink is

• A. $\sqrt{\frac{2 \sigma}{\pi d g}}$
• B. $\sqrt{\frac{3 \sigma}{\pi d g}}$
• C. $\sqrt{\frac{5 \sigma}{\pi d g}}$
• D. $\sqrt{\frac{7 \sigma}{\pi d g}}$

Answer 1

Answer: (A)

$\sigma \cdot(2 l)=\left(\pi r^{2} \cdot l\right) d \cdot g$
$ \Rightarrow r=\sqrt{\frac{2 \sigma}{\pi d g}}$