Science Projects And Inventions

YOU NEED:

• White cardboard
• Scissors
• A sharpened pencil stub
• Felt – tip – pen

Cut a circle about six inches (15 cm) in diameter from a piece of white cardboard.

Make a hole in the middle and push a sharpened pencil stub through it to make a top. Take the felt – tip pen, and draw a black circle on the disk as in the illustration. Guess what you will see you spin the top?

You will see small concentric circles and that too, two of them!

HOW DOES IT WORK?

The illustration reveals that XY drawn the diameter through the middle of the small circle, will intersect it at pots. As the disk spins, the spots move in almost a straight line compared to other spots along the little circle. The eyes see them for a longer time so as to generate two large circles on the disk.