derive  lens formula for convex lens when virtual image is formed.

derive lens formula  for concave lens.

Asked by Shomyajit Misra Misra | 24th Apr, 2014, 07:09: PM

Expert Answer:

Please post different questions as separate queries.

Derivation of Lens Formula for concave lens:

Let AB represent an object placed at right angles to the principal axis at a distance greater than the focal length f of the convex lens. The image A1B1 is formed between O and F1 on the same side as the object is kept and the image is erect and virtual.


lens formula


OF1 = Focal length = f

OA = Object distance = u

OA1 = Image distance = v

But from the ray diagram we see that OC = AB

From equation (1) and equation (2), we get

Dividing throughout by uvf

Answered by  | 25th Apr, 2014, 09:23: AM

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