Question 8
Structure of Matter and Kinetic TheoryA thin film of liquid is trapped between two glass plates. The force required to pull the plates apart will increase if the
- A.surface tension of the liquid is reduced
- B.perpendicular distance between the plates is increased
- C.area of the liquid surface in contact with the plates is increased.
- D.pressure of the air is decreased.
Show the answer and explanation
Answer: C (area of the liquid surface in contact with the plates is increased.)
Explanation
The plates are held together by surface tension acting over the wetted area, so a larger area of liquid in contact makes them harder to separate.