A person wears bifocal glasses and is reading a newspaper a distance of 20.0 cm away.The lower part of the lens is converging for reading and has a focal length of 70.0 cm.The upper part of the lens is diverging for seeing at distances far away and has a focal length of 50.0 cm.What is the uncorrected far point for the person?
A)20.0 cm
B)50.0 cm
C)70.0 cm
D)90.0 cm
E)120 cm

Question

Quizplus · Accepted Answer

The uncorrected far point for the person can be determined by considering the upper part of the bifocal glasses, which is diverging and has a focal length of 50.0 cm. Since diverging lenses are used to correct for myopia (nearsightedness), where the person can see objects clearly only when they are close, the focal length of the diverging lens gives an indication of the farthest point the person can see clearly without correction. Therefore, the uncorrected far point for the person is 50.0 cm.

A Person Wears Bifocal Glasses and Is Reading a Newspaper