Physic Labs

Problem 3

A transverse object of height HH is placed before a converging thin lens of focal length f>0f>0, perpendicular to its principal axis. Its distance from the lens is u=3fu=3f; use the convention that image distance v>0v>0 lies opposite the object and signed transverse magnification is M=−v/uM=-v/u. (a) Use the principal-ray construction to determine the image character and location. (b) Find the signed magnification and image height. (c) If a smaller object is placed at the same position, state what changes and what does not, explaining with the lens equation.
H′=MH=−H2H'=MH=-\frac H2
problems.proof.analysis

Magnification is the ratio of image to object height. The negative sign records that an object above the axis forms an image below it.