An object is placed at a distance of 20.4 cm from a thin convex lens along its axis.The lens has a focal length of 13.0 cm.What are the values,respectively,of the image distance and magnification?
A)7.94 cm and 0.569
B)35.8 cm and - 0.363
C)7.40 cm and -1.76
D)35.8 cm and -1.76
E)7.40 cm and - 0.363

Question

Quizplus · Accepted Answer

Using the lens formula (1/f = 1/v - 1/u), where f is the focal length and u is the object distance, we find the image distance v. Substituting f = 13.0 cm and u = -20.4 cm (object distance is negative in lens formula), we get v = 35.8 cm. The magnification m is given by -v/u, which results in -1.76.

An Object Is Placed at a Distance of 20