9 September 2014

Reflection Of Light : Science NCERT Notes


The path of light is always straight and never  curved. Light doesn’t bend. Examples to show that light travels in a straight line are light emitted by a torch light and light emitted from the headlights of a vehicle. The direction of light can be changed only by reflection.

Reflection of Light

The bouncing of light by any smooth surface, like a mirror, is called reflection of light.

Reflection Of Light, Science NCERT Notes, CBSE Notes, Class 7


Due to the reflection of light, the impression of an object formed in a mirror is called the image of the object. As the distance of the object from the mirror increases, the distance of the image also increases. The concept that images in a mirror are located at the same distance behind the mirror as the object in front of it is mainly used in interior decoration and in architecture to make rooms appear brighter and bigger. Moreover, placing a mirror near lights, chandeliers and table lamps reflects the light over a larger area, and makes the room appear brighter. Images that cannot be captured on a screen are called virtual images.

Left-Right Inversed

As the name suggests, images are inversed, i.e. the right part of an object appears on the left in its images, and the left part of the object appears to the right.
For example, the word ‘AMBULANCE’ is painted left-right inversed on the vehicle so that when the driver of a vehicle in front looks into his rear - view mirror, he can make out the word AMBULANCE quickly and give way.

Characteristics of an Image

The image formed by a plane mirror is:
  • The same size as that of the object
  • Left-right inversed
  • Erect and virtual
  • Formed behind the mirror at the same distance as the distance of the object in front from the mirror
mirror maze is created based on the principle of reflection in plane mirrors. The maze has several plane mirrors placed at fixed angles to each other. When a person enters a mirror maze, he finds several images of himself and several passages. There is only one passage that is real, while all the others are all just images.