Home›Science›Physics (continued)›What is Surface Tension?
◉ Science·2 min·Updated Mar 14, 2026

What is Surface Tension?

Surface Tension

Quick Answer

It is the property of a liquid that allows it to resist an external force. This occurs because the molecules at the surface are attracted to each other more strongly than to the air above. As a result, the surface behaves like a stretched elastic membrane.

Overview

Surface tension is a physical property of liquids that arises from the cohesive forces between liquid molecules. At the surface of a liquid, molecules experience a different environment than those in the bulk of the liquid. This difference leads to a net inward force, causing the surface to contract and minimize its area, which is why small objects, like a needle, can sometimes float on water despite being denser. The concept of surface tension is critical in many natural and industrial processes. For example, when you see water droplets on a car's windshield, they maintain a rounded shape due to surface tension. This property also plays a role in the way insects, like water striders, can walk on water without sinking, as their legs do not break the surface tension. Understanding surface tension is important in various scientific fields, including biology and chemistry. In biology, surface tension is vital for processes like the formation of cell membranes and the transport of nutrients in plants. In chemistry, it influences how substances mix or separate, affecting everything from cleaning products to paint. Thus, surface tension is not only a fascinating physical phenomenon but also a key factor in many everyday occurrences.

Frequently Asked Questions

Surface tension is caused by the cohesive forces between liquid molecules. Molecules at the surface are pulled inward by neighboring molecules, creating a tension that makes the surface behave like a stretched membrane.
As temperature increases, surface tension typically decreases. This happens because higher temperatures give molecules more energy, allowing them to move more freely and reducing the cohesive forces that create surface tension.
Yes, surface tension can be measured using various methods, such as the drop weight method or the Wilhelmy plate method. These techniques quantify the force acting at the surface of a liquid, providing a numerical value for surface tension.