A small luminous object is placed on the principal axis of a concave spherical mirror. When the object is 40cm from the mirror, a sharply focused image appears on a movable screen 60cm from the mirror on the object side.
Assume the sign convention in which real distances measured toward the mirror are positive and those measured away from the mirror are negative.
(a) Calculate the numerical value of the mirror’s focal length, including its sign.
(b) Determine the mirror’s radius of curvature.
(c) State whether the image is real or virtual, upright or inverted, and larger or smaller than the object. Justify your answer using the distances given.