A researcher uses a converging lens with focal length 300 mm

A researcher uses a converging lens with focal length 300 mm to view a specimen. The lens is placed 100 mm from the specimen.

(a) Where will the image be located?
____________ mm on the same side of the lens as the sample.

(b) What is the magnification?
____________

Solution

Focal length f = 300 mm

Object distance u = 100 mm

From the relation (1/v) -(1/u) = (1/f)

                         (1/v) -( 1/-100) =(1/300)

                         (1/v) +(1/100) =(1/300)

                                    (1/v) = (1/300) -( 1/100)

                                            = (1-3)/300

                                            = -2/300

                                         v = -300/2

                                           = -150 mm

(b). magnification m = v / u

                             = 150 mm / 100 mm

                             = 1.5