Two objects $A and B$ are placed at $15 \mathrm{cm} \mathrm{and} 25 \mathrm{cm}$ from the pole in front of a concave mirror having radius of curvature $40 \mathrm{cm}$. The distance between images formed by the mirror is:

An object is placed at a distance of $12 \mathrm{cm}$ from a convex lens. A convex mirror of focal length $15 \mathrm{cm}$ is placed on another side of the lens at $8 \mathrm{cm}$ as shown in the figure. The image of the object coincides with the object.

When the convex mirror is removed, a real and inverted image is formed at a position. The distance of the image from the object will be $\_\_\_ \mathrm{cm}$

An object is placed beyond the centre of curvature $C$ of the given concave mirror. If the distance of the object is $d_1$ from $C$ and the distance of the image formed is $d_2$ from $C,$ the radius of curvature of this mirror is:

Find the distance of the image from object $O,$ formed by the combination of lenses in the figure:

Curved surfaces of a plano-convex lens of refractive index ${\mu }_1$ and a plano-concave lens of refractive index ${\mu }_2$ have equal radius of curvature as shown in figure. Find the ratio of radius of curvature to the focal length of the combined lenses