$3.$A single bi$-$concave lens $($a lens with two concave surfaces$)$ made of diamond $($index of refraction $n=2\mathrm{.}42)$ has surfaces with radii of curvature $r_1=-30\mathrm{.}0cm$ and $r_2=30\mathrm{.}0cm.$ What is the focal length of the lens in air?

Tries $0/12$

If an object is placed at $p=19\mathrm{.}0cm$ from the lens, where is the image? $($Use a positive sign for a real image or a minus sign for a virtual image.$)$

Tries $0/12$

If the object has a height of $h=1\mathrm{.}40cm,$ how large is the image? $($Use a positive sign for an upright image or a minus sign for an inverted image.$)$