Concave Mirror: It is a spherical mirror whose outer surface is polished and inner or concave side is reflecting surface.
Convex Mirror: It is a spherical mirror whose inner surface is polished and outer side or convex side is the reflecting surface.
f = m4\frac{m}{4}4m = f = d4\frac{d}{4}4d
f = 204\frac{20}{4}420 = 5cm
