Why does a spoon or pencil placed in a glass of water appear to be bent to broken?

Answer 1

Light always travles in the the path with the shortest possible time ,from A to B say.

Light travles slower in water than in air.

Now, take this analogy (thanks to Richard Feynman):

Imagine you are a life guard and you want to save a drowning man further along the beach. You obviously want to get there in the shortest time. Should you run to the shore, and swim to him all in a straight diagonal line? Or should you travel all the way to him on the beach and then swim perpendicularlly towards him? Remeber that you are slower in water than on the beach (just like the light).

The answer is, that the shortest route is somewhere in between these two, and so you should go in a slightly bent path to go in the shortest time.

Since you are like the light, in that you are slower in one medium than the other in this analogy, then the light will also bend as it enters water, hence the distortion of a spoon in a glass of lemonade.

Really hope this helps.

Answer 2

This phenomenon is known as refraction, where light bends as it passes from one medium to another with a different optical density, such as air to water. The bending of the light can make objects appear distorted or bent when viewed from outside the water.