• Light is never curved and the path is always straight.
  • Only reflection can change the direction of light.
  • When light bounce by smooth surface then it is called as reflection of light.

Image

  • When the impression of an object created in a mirror due to the reflection by light then it is known as the image of the object.
  • A distance of the image increases with the distance increase in the object.

Characteristics of an image

  1. The image is left-right inversed
  2. The size is same like object.
  3. Virtual and erect

Spherical mirror

  • Also called as curved mirrors due to having curved reflecting surfaces.
  • At each hemisphere, two types of the curved surface occur
  • Concave mirror and convex mirror are the two type of spherical mirror.

Concave mirror

  • A concave mirror is one which has a concave reflecting surface.
  • Also known as converging mirror.
  • A dentist uses concave mirrors.
  • Also used in headlights of scooters and cars 

Convex mirror

  • A convex mirror is one which has a convex reflecting surface.
  • Also called as fish eye mirror or diverging mirror
  • The image formed is virtual, diminished and erect.
  • As a security measure used in supermarkets, shops and ATM centers.

class 7 light

Opaque spherical surface

  • The silvered surface in an opaque spherical surface acts as a mirror.
  • A convex mirror will have convex side silvered and concave will have concave side silvered

Concave lens

  • When at least one surface of a lens is curved inwards then it is known as a concave lens.
  • The rays are divergent.
  • The centre is thinner than the edges.
  • The image formed is virtual and upright.

Convex lens

  • An object becomes magnified.
  • Light rays are converged.
  • The image formed is erect, magnified and virtual.

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Application of lenses

  • Peepholes
  • Magnifying glasses
  • Bioscopes
  • Cameras
  • Telescopes
  • Binoculars
  • Projectors
  • Microscopes

Dispersion of light through a prism

  • Have a glass prism
  • Then let the beam of sunlight to go through the small hole in the window to fall on one side of a prism
  • The light when passing through prism bends.
  • Now let the light go out from another side of the prism to fall on white paper.
  • The colors will disperse.

class 7 light

Recap

  • Light is never curved and the path is always straight.
  • Only reflection can change the direction of light.
  • The distance of the image increases with the distance increase in the object.
  • The image is left-right inversed
  • A concave mirror is one which has a concave reflecting surface.
  • A convex mirror is one which has a convex reflecting surface.