Question
Question: An eye specialist prescribes spectacles having a combination of a convex lens of focal length 40 Cm ...
An eye specialist prescribes spectacles having a combination of a convex lens of focal length 40 Cm in contact with a concave lens of focal length 25 cm. The power of this lens combination is:
A
+1.5 D
B
-1.5 D
C
+6.67D
D
-6.67D
Answer
-1.5 D
Explanation
Solution
: Power of the lens combination is
=−1.5 m−1=−1.5D