Question
Sat February 09, 2013 By: Arathi M
 

A U-shaped wire is dipped in a soap solution and removed. the thin soap film formed between the wire and the light slider supports a weight of 1.5/100 N. The length of the slider is 30 cm. What is the surface tension of the film?

Expert Reply
Sat February 09, 2013

The weight that the soap film supports, W = 1.5 × 10–2 N

Length of the slider, l = 30 cm = 0.3 m

A soap film has two free surfaces.

?Total length = 2l = 2 × 0.3 = 0.6 m

Surface tension,

 = 

Therefore, the surface tension of the film is 2.5 × 10–2 N m–1.

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