Question

An object of height 1 centimeter is placed 6 centimeters to the left of a converging lens whose focal length is 8 centimeters, as shown on the diagram above.

(a) Calculate the position of the image. Is it to the left or right of the lens? Is it real or virtual?

(b) Calculate the size of the image. Is it upright or inverted?

(c) On the diagram, locate the image by ray tracing.

(d) What simple optical instrument uses this sort of object-image relationship?

Answer 1

(a) 1/f = 1/d_o + 1/d_i … 1/8 = 1/6 + 1/d_i … d_i = –24 cm, left of lens, virtual

(b) M = – d_i / d_o … M = – (–24) / 6 = +4 … M = h_i / h_o … 4 = h_i / 1 cm … h_i = 4 cm, upright

(c)

(d) Magnifying glass, or telescope / microscope.