CBSE Class 10 Science 2018 · Paper 31/1 · Question 26

Ray diagram: the object AB ($4.0$ cm) stands $30$ cm from O, between $F_1$ and $2F_1$. A ray from B parallel to the axis is refracted through $F_2$, and a ray from B through O goes undeviated; the two meet at $B^{\prime }$. Position of the image: $60$ cm from the lens on the other side, beyond $2F_2$ (check: $\frac{1}{v}=\frac{1}{20}-\frac{1}{30}=\frac{1}{60}$, so $v=+60$ cm). Size of the image: $8.0$ cm; the image is real and inverted ($m=-2$). Ratio of the size of the image to the size of the object $\approx 2:1$.