Problem 3

On an optical bench, a thin converging lens of focal length

f=10.0\,\mathrm{cm}

is used with an object of height

h_o=2.00\,\mathrm{cm}

placed on the principal axis, initially at distance

u=30.0\,\mathrm{cm}

. Work in air and in the paraxial approximation. For a real object take

u>0

; a real image has

v>0

. Define transverse magnification by

M=h_i/h_o=-v/u

. (a) Find the image distance and magnification, and state whether the image is real or virtual and upright or inverted. (b) Find the image height. (c) Move the object to

u=15.0\,\mathrm{cm}

and repeat the position, magnification, and image-character determination, then compare the two placements.

problems.proof.stepOf

problems.proof.prevStep problems.proof.nextStep

\frac1f=\frac1u+\frac1v

problems.proof.analysis

For a real object under the stated sign convention, the thin-lens equation is $1/f=1/u+1/v$ . It applies in the paraxial regime specified in the problem.