question_answer

The maximum force, in addition to the weight required to pull a wire of 5.0 cm long from the surface of water at temperature\[{{20}^{o}}C\], is 728 dynes. The surface tension of water is

A) 7.28 N/cm

B)                      7.28 dyne/cm

C)             72.8 dyne/cm

D)                      \[7.28\times {{10}^{2}}\]dyne/cm

Correct Answer: C

Solution :

                \[T=\frac{F}{2l}=\frac{728}{2\times 5}\] \\[T=72.8\ dyne/cm\]