Practice question

**Mirror formula** 1/f = 1/v + 1/u governs spherical mirrors, f = R/2, R radius of curvature (m), u object distance (m), v image distance (m), sign convention: distances in front of mirror negative for real is convention but magnitude used, magnification m = -v/u, concave forms real inverted when object beyond F, virtual erect within F. Focal length: f = -15 cm (concave mirror). Image distance: v = -30 cm (real image, same side as object). Mirror equation: (1/v) + (1/u) = (1/f) . (1/-30) + (1/u) = (1/-15) ⇒ (1/u) = (1/-15) + (1/30) = (-2 + 1/30) = (-1/30) . u =