Wilhelmy plate

A Wilhelmy plate is like a flat thin piece of metal that we use to measure how much tension there is on a liquid surface. Imagine you have a cup of water and you decide to put a small piece of metal in it, then you slowly pull it out of the cup.

As you do this, you start to see that the water forms a layer around the metal (kind of like a clingy coating). This is because of the surface tension of the water - the attraction between water molecules causes it to form that layer.

Now, if you keep pulling the metal out of the water, eventually the layer will break apart, and the metal will become dry.

The Wilhelmy plate is designed to measure the force required to pull that plate out of the water. By measuring how much force is required to break that layer of water around the metal plate, we can calculate the surface tension of the water. This information is helpful in many scientific experiments because it can give us insight into how liquids behave, and it helps us understand how different properties of liquids (like viscosity) affect their behavior.