Light rays that pass or appear to pass through the _______ are reflected by the curved mirror parallel to the principal axis.   principal focus   center of curvature   pole   Hint Half-n-half Clue   If the focal length of a spherical mirror is 50 cm, then its radius of curvature is _______ cm.   100   25   50   Half-n-half Clue   A concave mirror has a _______ principal focus.   virtual   real   If the object is placed at the principal focus in front of a concave mirror, the image formed is _______.   diminished   inverted   also at the principal focus   Half-n-half Clue   To obtain an erect and magnified image, the object must be placed before a concave mirror between _______.   the pole and the principal focus   the principal focus and the center of curvature   the center of curvature and infinity   Half-n-half Clue