A frame made of metalic wire enclosing a surface area A is covered with a soap film. If the area of the frame of metallic wire is reduced by `50%` the energy of the soap film will be changed by:

Options

A. `100%`
B. `75%`
C. `50%`
D. `25%`

Answer

C

Explanation

`W = T xx 2A`
`W_1 = T xx 2 (A//2) = T xxA`
% decreases in energy
`(W-W_1)/Wxx100 = (2TA-TA)/(2TA)=50%`