Physics - Geometrical Optics Question with Solution | TestHub

Magnification, $\mathrm{m}=-\frac{1}{4}$ (Since the image is real and inverted, it is taken as negative) $$\begin{array}{rl}& \therefore \mathrm{m}=\frac{\mathrm{v}}{\mathrm{u}}=-\frac{1}{4}\\ & \mathrm{v}=-\frac{\mathrm{u}}{4}\end{array}$$ Lens formula, $\frac{1}{\mathrm{v}}-\frac{1}{\mathrm{u}}=\frac{1}{\mathrm{f}}$ $$\begin{array}{rl}& -\frac{4}{u}-\frac{1}{u}=\frac{1}{f}\\ & u=-5f\end{array}$$