Question

Which property of light makes a pencil cast a shadow when it is held in front of a light source?

Answer 1

Hint:Light is a form of electromagnetic radiation and it has various properties. There are three main laws that light is governed by, within which lies the answer to this question.Light is a form of energy which is produced by a light source.

Complete answer:
Light is a form of electromagnetic radiation of a certain wavelength. It is made of photons that behave as both – particles and waves too. Light also travels much faster than sound energy. And unlike sound, it can travel in vacuum and does not need any medium.

A shadow is a dark area or shape that is produced by a body that comes between a light source and a surface. The formation of shadows is proof that light travels in a straight line, which is one of the main laws governing light. When an object comes in front of a light source, it blocks the direct light rays that are coming at it.

And, as light cannot pass through opaque objects, there is no light reaching the surface behind said object. Light fills up all of the space around the object, but behind the object forms a shadow.Moreover, this shadow doesn’t appear completely dark as some light rays bounce off the object and reflect on the surface with reduced intensity.

Therefore, when a pencil is held in front of a light source and a shadow is formed, it shows light’s property of travelling in a straight line.

Note:Such questions look at basic knowledge of phenomenon around us. Understanding the properties of light is important and then learning examples of such phenomenon, which will help you answer these questions. The other properties of light include it’s behaviour as a wave and as particles.