Physics - Geometrical Optics Question with Solution | TestHub

When an object is placed at a distance of 25 cm from a concave mirror, the magnification is $m_1$. The object is moved 15 cm farther away with respect to the earlier position, and the magnification becomes $m_2$. If $m_1/m_2=4$, the focal length of the mirror is (assume image is real; $m_1,m_2$ are numerical values)