A wire forming a loop is dipped into soap solution and taken out so that a film of soap solution is formed. A loop of 6.28 cm long thread is gently put on the film and the film is pricked with a needle inside the loop. The thread loop takes the shape of a circle. Find the tension in the thread. Surface tension of soap solution `=0.030Nm^-1`.

Answer

A, C, D

Explanation

We know `/_\P=45/R`
then `T=/_\P`
`piR^2=45/R`
`=piR^2=4xx0.030xx3.14xx10^-2N`
`=4xx10^-3N`