Question

how do we determine the sign of focus in case of lenses​

Answer 1

focus in convex lens is positive and in concave negative✔✔✔✔

Answer 2

In lenses if the image is formed on focus is on the right side of the lens . Then it is +ve

Like in convex lens .

But if image formed on focus is on left side then its - ve.

Like in Concave lens

Hope it helps ....

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