Physics - Geometrical Optics Question with Solution | TestHub

A tube of length 30 cm has its inner lateral surface blackened. Two lenses of focal lengths 10 cm and 20 cm are fixed at the ends of the tube. For same beam, intensities of spots on screen are $I_1$ and $I_2$ for arrangement (1) and arrangement (2). If the ratio of ${\mathrm{I}}_2:{\mathrm{I}}_1$ is of the form ${\mathrm{N}}^2$, find N .