Class 7 Physics Light Lens

Lens

A Lens is a type of mirror which refracts the light instead of reflection.Refraction is the bending of a light when it enters a medium. Here the medium is Lens.

  • Lens are of various types but the two most important types are convex (on Bi-convex) and concave (or Bi-concave) lens

  • Convex lens are thicker in middle than the edges whereas concave lens are thinner at the middle than at the edges
  • Lenses are transparent and light can pass through them.
  • Convex lens are also called convergent as they concentrate (bend inward) the light falling on it.
  • Concave lens are also called divergent lens as they expand the light (bend outward) falling on it.

  • Real images are formed using convex lens by placing them in between the object and the screen.

  • Virtual images are also formed by convex lens which is erect and larger in size.
  • Concave lens do not form real images. They only form virtual images which are always erect and smaller in size.
  • Applications of lens include magnifying glass, telescopes, contact lens, cameras etc.

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