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:

only p and r

... .........

Answer 2

Answer:

p and r will have +ve focal lengths