Question

Question 17
A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?

Answer 1

Power, $P=+1.5D$
$P=\frac{1}{f\left(inmetres\right)}orf=\frac{1}{P}=\frac{1}{+1.5}=0.66m$
The focal length,f = 0.66m
A convex lens has a positive focal length. Hence, it is a convex lens or a converging lens.