Concave/converging mirror: * produces a virtual image when object distance(u) exceeds its focal length(f). \(\frac{1}{f} = \frac{1}{u} + \frac{1}{v}\) \(\frac{1}{v} = \frac{1}{f} - \frac{1}{u}\) \(\frac{1}{15} - \frac{1}{10} = \frac{2 - 3}{30}\) \(\frac{1}{v} = \frac{-1}{30}\) v = -30cm( virtual image) but m = \(\frac{v}{u} = \frac{30}{10} = 3\) Note that the negative sign only shows the placement of the image. It does not affect the magnification.