Question

In case of angle of contact is obtuse the free Surface of liquid in capillary tube is​

Answer 1

Answer: When the liquid surface is curved concave upwards, the angle of contact is acute and when the liquid surface is curved convex upwards, the angle of contact is obtuse

Explanation: hope it helps

Answer 2

Answer: The answer to this question is-

In case of angle of contact is obtuse then the free Surface of liquid in capillary tube will be convex upwards (Ф>90) and hence the liquid height will drop.

Explanation:

The forces acting on liquid molecules are

(i) Force of cohesion Fc (acts at an angle of 45° to the vertical) if liquid molecules are in contact with solid (i.e., the capillary tube wall).

(ii) Adhesion force Fa (acts outwards at right angle to the wall of the tube).

Angle of contact is determined by the characteristics of the solid and liquid in contact as well as the medium that is present above the liquid's free surface. Wax can make a glass capillary tube waterproof by coating it with wax. The contact angle widens and becomes acute. It doesn't allow water to rise. Instead, because of the obtuse angle of contact, it falls into the tube.

• The liquid meniscus will be concave upwards if is acute, or < 90°.

• The liquid meniscus will be plane if it 90 degrees.

• The liquid meniscus will be convex upwards if it obtuse, or >90°.

• A liquid will soak a solid surface if the angle of contact is sharp, or less than 90°.

• Obtuse angle of contact, or an angle greater than 90 degrees, prevents liquid from wetting a solid surface.

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