Ray Optics and Optical Instruments question bank (Physics)

$A$ simple microscope is a combination of two lenses in contact. Their powers are $+20$ $D$ and $-4$ $D$. The distance of distinct vision is $25$ cm. When seen through the microscope, the size of an object $3$ mm high is (in $cm$)

The angle of minimum deviation produced by a thin prism in air is $\delta_1$. What will be the minimum deviation $(\delta_2)$ if the prism is immersed in liquid? Given: refractive index of glass with respect to air $^a n_g = \frac{3}{2}$ and refractive index of liquid with respect to air $^a n_l = \frac{4}{3}$.