The upper and lower portions in common type of bi-focal lenses are respectively

Question 126 The upper and lower portions in common type of bi-focal lenses are respectively
A> concave and convex
B> both concave of different focal lengths
C> convex and concave
D> both convex of different focal lengths
Answer: both convex of different focal lengths
Explanation: most convex lenses in the lower half of the frame and the least convex lenses on the upper part. Means both convex lenses of different focal lengths.

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