Question

Consider the optically denser lenses P,Q, R and S drawn below. According to Cartesian sign convention which of these have positive focal length?

(A) Only P
(B) Only P and Q
(C) Only P and R
(D) Only Q and S​

Answer 1

Answer:

I think it is b) only p and q

Step-by-step explanation:

only convex, plano-convex, or concavo-convex has +ve focal length

Answer 2

Answer:

b is answer

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