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please explain sign convention of sphereical lenses. please mention negative or positive for u, f, v etc
Asked by Tejas Kulkarni | 10 Dec, 2014, 22:29: PM
answered-by-expert Expert Answer
The sign convention of spherical lenses are:
  1. All distance are measured from the optical centre of the lens.
  2. The distance measured in the same direction as that of incident light are taken as positive and the distance measured against the direction of incident light are taken as negative.
  3. The distance measured upwards, perpendicular to the principal axis are taken as positive on the other hand distance measured downwards to the pricipal axis are taken as negative.

That means that as the object is placed on the left side of the lens, u will be negative.

Focal length of a convex lens is taken as positive and on the other hand focal length of a concave lens is considered as negative.


Answered by Jyothi Nair | 11 Dec, 2014, 09:07: AM

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