• $summary_{type}$: concept
• $word_{count}$: 180

Spherical mirrors (concave and convex) follow the mirror formula 1/v + 1/u = 1/f, where f = R/2. Using the New Cartesian sign convention, all distances are measured from the pole; the direction of incident light is taken as positive. Concave mirrors have negative f; convex mirrors have positive f. Magnification m = -v/u gives information about image orientation (negative = inverted, positive = erect) and size. Concave mirrors can form both real and virtual images depending on object position relative to F and C. Convex mirrors always form virtual, erect, diminished images, making them ideal for rear-view mirrors with their wide field of view. The focal length of a mirror is independent of the surrounding medium since reflection does not depend on refractive index. For moving objects, image velocity is related to object velocity by $v_{image}$ = $m^{2}$ × $v_{object}$ along the principal axis. These fundamentals appear in approximately 1-2 questions per JEE paper.