A _______ mirror has a virtual principal focus.   concave   convex   If an object is placed before a convex mirror (as shown in the ray diagram), the image formed is _______.   virtual   real   A concave mirror has a _______ principal focus.   real   virtual   If an object is placed before a convex mirror (as shown in the ray diagram), the image formed is _______ in size.     diminished   enlarged   The geometric center of the curved mirror is called _______.   pole   principal axis   centre of curvature   Hint Half-n-half Clue