Colourful sections

What you can do here
Look at the pattern on the still disk. Start spinning it. Slowly increase the spinning speed. What can you see? Experiment by rotating the disk with various angular velocities. Pay attention to what you can see when you blink.


How it works
When the rotation speed is low, you can see blurred colour streaks on the edges of the yellow and blue sectors. The explanation of this phenomenon may be similar to Benham’s top. When the wheel rotates fast, you see a uniform green surface. This colour comes from mixing yellow and blue. From time to time, blue-and-yellow flashes (fragments of the disk) are visible when you blink. When you close your eyes for a moment, just a split second, the eye collects the signals and sends them to the brain, but not enough colours reach it to make it green.


Interesting facts
With every blink, the eyelids moisten the surface of the eye and remove dust or germs. On average, people blink once or twice every 10 seconds and every blink takes a third of a second. So, in a 12-hour the period you spend around 25 minutes blinking.