A. Reflection and Spherical Mirrors

$f = \frac{R}{2}$

$\frac{1}{v} + \frac{1}{u} = \frac{1}{f}$

$m = -\frac{v}{u} = \frac{h_i}{h_o}$

Sign rules: u always negative; concave: f < 0, R < 0; convex: f > 0, R > 0.