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The Surface Tension of Liquid

A liquid is composed of a group of tiny molecules. Each molecule attracts by others in its neighborhood. When the molecules try to leave the liquid, they will be retarded by a force pulling them back. The liquid tries to retain the smallest and smoothest surfaces. The surface tension refers to the force per unit area on the surface of a liquid. This experiment uses the method by hanging and lifting a ring to measure the magnitude of surface tension of a liquid. Various liquids are selected. Difference in their surface tensions can be observed. 













Attach to the ring. Pull the ring out of the surface and measure the displacement of the spring then determine the surface tension.

Masses & Copper Dish
Vary the load hanging from the spring and then determine the spring constant.

Dip the ring under surface of a liquid and then withdraw.
The force which requires to pull the ring out of the surface is equal to the weight
of the ring.

Use different liquids and compare their surface tensions.

Z-axis Adjustable Stage
To adjust the vertical height of the bottom of the ring.

Scale Rule
To measure the displacement of the spring.


 The Surface Tension of Liquid


Department of Physics (Digital Archive Project of NTU General Physics Laboratory)
National Taiwan University