Optics: Serway Problem $23\mathrm{.}31$

A converging lens has a focal length of $10\mathrm{.}0$ cm $.$ Locate the images for object distances of

a$.20\mathrm{.}0$ cm $,$

Answer:

$20\mathrm{.}0$ cm beyond the lens; real, inverted, $M=-1\mathrm{.}00$

b$.,10\mathrm{.}0cm,$ and

Answer:

No image is formed. Parallel rays leave the lens.

c$.,5\mathrm{.}00cm,$ if they exist. For each case, state whether the image is real or virtual, upright or inverted, and find the magnification.

Answer:

$10\mathrm{.}0$ cm in front of the lens; virtual, upright, $,M=+2\mathrm{.}00$