To measure surface tension of a Liquid
The aim of this physics experiment is to use a domestic single-beam weighing scale to straight away measure the surface tension of a liquid.
Surface tension is defined as the quantity of energy necessary to increase the surface area of a liquid by a unit amount. The unit for Surface tension is expressed in joules / square meter or (J/m2). Also, the units can be expressed as force per unit length, newton / meter (N/m). at times, when the forces are very small, surface tension is expressed in milli-newton per meter (mN/m ” 1 mN is 1/1000 N).
The molecules of the liquid attract each other and forces arise between them. This is the hydrogen bonds that exert the force.
This experiment makes use of a single beam balance to measure the force (surface tension) that is exerted on a needle, which is floating on the surface of the liquid (water). The needle is attached to the balance, and the force that is required to pull the needle out of the water is measured. The surface tension of the water provides the resistance. From these measurements, we calculate the surface tension of water.
Materials and Equipment
To construct a domestic single-beam balance (see Figure 1 in the Experimental Procedure section), the following is needed: