Ripples
Some children were interested in finding concentric circles in nature and started experimenting with dropping rocks into a puddle to watch the ripples they created. One of the nursery practitioners took some photos of the ripples made in the water and asked the children what they could see.
“Dropped stones into water”
“Made a big splash”
“And a little splash”
Teacher: Are there any concentric circles?
A child then recalled that concentric circles are:“Two or more circle that are inside each other”
A child pointed to the image and said:“There one”
If they wanted to continue thinking investigating the ripples in the water there are a few things that that children could try.
The children could try creating circular ripples by repeatedly dipping a circular object in and out of a tub of water and seeing the waves form. They could change the speed and the size of the waves they created by varying how quickly they dipped the object and how much energy they dipped the object with. The children might find it interesting to see how the ripples change as the objects changed shape. Similarly they could also place some obstacles in the tank and see how the waves travel around and reflect off of these.
The children could also try using multiple objects and dipping them in the water at the same time. This would cause multiple sets of concentric circles to form. Where these circles meet, the children might get to see the ripples interfering with each other.
Mathematicians use sine and cosine waves when dealing with complex equations and make use of the wave interaction behaviour (like the ripples cancelling each other out in the water) to help them solve problems. In the image below, there are two waves, one red and one blue. When both of these two waves are created, they cancel each other out, giving the flat black line.
In the image below, we can again see two waves, one red and one blue, and we can see that when these waves interact, we get a different wave, which is given by the black line.
Waves can create complex patterns such as Chladni figures. These are patterns formed on vibrating plates and there are lots of videos of these being generated online. To see more about concentric circles in nature see our article on concentric circles in nature.
