Bending Pencil
Playing around with light was never this much fun before we discovered the marvel of the bending pencil. There are numerous phenomena associated with light that have fascinated mankind throughout history. This fascination can be traced back to the principle of formation of shadows, which has been used by the ancient cavemen to keep a track of time. Many effects can be associated with light including reflection, refraction, and photoelectric effect. Reflection takes place on many surfaces such as water, a spoon, or any other shiny surface.
Refraction is another phenomenon usually associated with light, and is the source of this phenomenon of bending a pencil. A coin lying at the bottom of a bucket filled with water appears so because of refraction. Similarly, a pencil appears bent for the same reason.
So let us carry out an activity to see a bent pencil.
The materials required for carrying out this experiment are a pencil, a transparent cup, and some water. Fill the jar halfway with water, dip the pencil into water and observe the pencil from different angles, from the top, bottom and the sides. The pencil appears bent in which of the three directions?
When the glass jar is looked at from the side, the pencil appears bent. This is because light travels slower through water than through air. As the light enters the glass of water it refracts (changes direction) and as it leaves the glass it changes again – therefore making the pencil look bent!
