Physics

Problem

A small drop of water of surface tension

\sigma

is squeezed between two clean glass plates so that a thin layer of thickness

d

and area

A

is formed between them. If the angle of contact is zero, the force required to pull the plates apart is: (A)

\frac{\sigma A}{d}

(B)

\frac{2\sigma A}{d}

(C)

\frac{4\sigma A}{d}

(D)

\frac{8\sigma A}{d}