Question.
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 ?
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 ?
solution:
Given, power, $\mathrm{P}=+1.5 \mathrm{D}$
Power, $P=\frac{1}{f}$
or $f=\frac{1}{P}=\frac{1}{+1.5}=\frac{10}{15}=+\frac{2}{3}$
or $\mathrm{f}=+0.66 \mathrm{~m}=+66 \mathrm{~cm}$
The lens is a convex (or converging) lens.
Given, power, $\mathrm{P}=+1.5 \mathrm{D}$
Power, $P=\frac{1}{f}$
or $f=\frac{1}{P}=\frac{1}{+1.5}=\frac{10}{15}=+\frac{2}{3}$
or $\mathrm{f}=+0.66 \mathrm{~m}=+66 \mathrm{~cm}$
The lens is a convex (or converging) lens.