Which of the following defines the center of curvature of a curved mirror ?   the center of the hollow glass sphere of which the curved mirror was (previously) a part   the radius of the hollow glass sphere of which the curved mirror was (previously) a part   the geometric center of the curved mirror   Hint Half-n-half Clue   If the object is placed at the center of curvature in front of a concave mirror, the image formed is _______.   erect   also at the center of curvature   virtual   Half-n-half Clue   If the focal length of a spherical mirror is 50 cm, then its radius of curvature is _______ cm.   100   50   25   Half-n-half Clue   Light rays that pass through the _______ are reflected back by the curved mirror along the same path.   pole   principal focus   center of curvature   Half-n-half Clue   If an object is placed before a convex mirror (as shown in the ray diagram), the image formed is _______ in size.     diminished   enlarged