Question

Two parallel glass plates are dipped partly in a liquid of density ′d′ keeping them vertical. If the distance between the plates is ′x′, surface tension for the liquid is T and angle of contact is θ, then rise of liquid between the plates due to capillary action will be:

A. T cos θ/xd
B. 2T cos θ/xdg
C. 2T/xdg cos θ
D. T cos θ/xdg

Answer 1

The correct formula for the rise of liquid between two parallel glass plates due to capillary action is 2T cos θ / xdg, so the answer to the student's question is B. 2T cos θ / xdg.

Step-by-step explanation:

The student has asked about the height to which a liquid rises between two parallel glass plates due to capillary action. In the context of capillary action in a tube, the formula for the rise of liquid is given by h = (2T cos θ) / (pgr), where h is the height of the liquid rise, T is the surface tension of the liquid, θ is the contact angle, r is the radius of the tube, p is the density of the liquid, and g is the acceleration due to gravity.

When we apply this formula to two parallel plates where the space between the plates represents a very wide tube (and thus the radius r tends towards half the distance x between the plates), we modify the formula to h = (2T cos θ) / (pdgx). Therefore, the correct answer to the student's question is B. 2T cos θ / xdg, which accounts for the liquid density (‘d’), distance between the plates (‘x’), surface tension (T), gravity (g), and the contact angle (θ).