Slide the object along the axis and flip the mirror between concave and convex. The bench solves 1/f = 1/v + 1/u and reports the image distance, magnification and whether it is real or virtual.
Image 1/f = 1/v + 1/u
Real, inverted
Image distance v15.0 cm
Magnification m-0.50
Image height h_i-2.00 cm
Object distance u30 cm
Focal length |f|15 cm
Object height h_o4 cm
Radius R = 30 cm · sign rule: f > 0 concave, f < 0 convex; v > 0 real (in front), v < 0 virtual (behind)
Tip: on a concave mirror, slide the object inside the focal point (u < |f|) and the image flips to virtual, upright and magnified — the make-up-mirror case.