Stopping Light

As long as the sun shines, it’s always there following you around to wherever you go. You can see it, but you can’t touch it. What is it?

We have shadows because light moves in a certain way. It travels outward from its source, like the sun or torch light. As long as nothing is in the way, the light waves move in one direction at a speed of 300,000 kilometers per second. 

That is like traveling around the world seven times in one second! Nothing travels faster than light waves. But when some of the light waves hit something – you, or a tree – they are stopped. Then, on the other side of the thing that stopped the light waves, there is a dark space – a shadow. 

Things in a dark room have no shadows because there are no light waves traveling through the room. And on cloudy days, things have no shadows because the clouds break up the light waves from the sun. The clouds soak up some of the waves and scatter the rest of them in all directions. When the light waves scatter and bounce instead of moving in one direction, no shadows are formed. 

You can see things in your room at night because of the light from the bulb. Try being in a thick jungle in the middle of the night, and you’ll realize the importance of light for our sense of sight. That is why some species of fish very deep down in the ocean do not have eyes because the sunlight doesn’t reach those depths.

Experiment: Make a shadow clock 

Materials: 
paper plate, spool, pencil

Steps:
1.    Glue the spool to the center of the paper plate.
2.    Place a pencil in the hole of the spool, with the point up.
3.    Place the paper under the sun early in the morning.
4.    Draw a line down the shadow the pencil makes on the paper plate.
5.    Write the hour next to the line you traced.
6.    Repeat steps 4 and 5 after every hour until the sun goes down.

Shared by Surain A. Victor

Guest Blogger