Convex mirror focal length, \(f = +15\ cm\). Object distance, \(u = −10\ cm\). Using the mirror formula, \(\frac 1v-\frac 1u=\frac 1f\).
\(\frac 1v=\frac 1f-\frac 1u\)
\(\frac 1v=\frac {1}{15}+\frac {1}{10}\)
\(\frac 1v=\frac {25}{150}\)
\(\frac 1v = \frac 16\)
\(v=6\ cm\). A positive \(v\) indicates the image is formed behind the mirror.
Magnification, \(m=-\frac {\text {Image\ distance}}{\text {Object\ distance}}\) or \(m =-\frac vu\).
\(m=-\frac {6}{-10}\)
\(m =+0.6\)
A positive magnification indicates a virtual and erect image.