Type Here to Get Search Results !

# Light :CBSE CLASS 7

CONTENT LIST

## Light

Light is a form of energy which enable us in seeing objects. When light falls on any object, some of the light gets reflected. The reflected light comes to our eyes and we can to see an object.

## Ray of light

The direction of path of light travelled in a medium is called rays of light.

## Beam of light

A group of rays of light is called beam of light. Beam of light may be parallel , convergent and divergent .

## Path of Light

Light travels in a Straight Line.

## Reflection of Light

When a ray of light falls on surface and the light ray bounces back, This phenomenon is called the reflection of light.

## Type of reflection

### Diffuse reflection

When light reflected from a smooth surface at a definite angle is called Specular reflection, whereas diffuse reflection is produced by rough surfaces that tend to reflect light in all directions

The angle at which light hits a reflecting surface measured from normal at the point of incedence is called the angle of incidence

The angle at which light bounces off a reflecting surface measured from normal at the point of incedenceis called the angle of reflection

## law of reflection

The law of reflection states that, on reflection from a smooth surface, the angle of the reflected ray is equal to the angle of the incident ray & incedent ray,reflected ray & normal lies on same plane.

An object is anything that is being viewed.e.g., when one looks at a tree through a mirror or any other optical device the tree is referred to an optical object.

An image is the copy of an object produced at a point in space by a mirror, lense or other optical device.

## Image formed by plane mirror

Image formed by a plane mirror is always erect and virtual .

The size of the image formed by a plane mirror is equal to that of the object.

The image formed by a plane mirror is as far behind the mirror as the object is in front of it.

The image formed by a plane mirror is laterally inverted. (turned by 180 degree)

## Real and Virtual image

Real image can be taken on screen but virtual image can't be taken on screen

## Spherical mirror/Curved mirror

Concave and convex mirrors are known as spherical mirror because their reflecting surfaces are the parts of hollow sphere of glass.

## Concave mirror

Outerside polished & innersite will be reflecting /shinysurface

It form real/virtual image

It form bigger/smaller image

It is used by doctor,densist,barbar shop to enlage image size

## Convex mirror

Innerside polished & outersite will be reflecting surface

It form virtual image

It form smaller image

It is used car

## Image formed by the lense

### Lense

A lens is a piece of transparent glass which concentrates (Converage) or disperses (diverse)light rays when passes through it

A lense which converge the light rays coming towards is called Converging lenses . whereas diverging lenses are lenses which diverge the rays coming towards them.

coverging lense is also called convex lense

diverging lense is also called concave lense

## Spectrum of light

When light passes through a glass prism or through a drop of water then spectrum is the range of different colours is produced . A rainbow shows the colours in the spectrum.
The colours of the spectrum of white light are violet, indigo, blue, green, yellow, orange and red (VIBGYOR).