Rules of Drawing Ray Diagram in Lens

  • Rays of light incident in a direction through the optical centre of a lens is refracted along the same straight line without any deviation (Fig: A and B)
  • Rays incident in a direction parallel to the principal axis after refraction passes through the principal focus (in the case of a convex lens) [fig (C)] or appear to diverge from the principal focus (in the case of a concave lens) [fig (D)].
  • A ray of light incidents through the principal focus (in the case of a convex lens) [fig (E)] or directed towards the principal focus (in the case of concave lens) [fig (F)] after refraction through the lens becomes parallel to the principal axis.

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