$A$ prism with a refractive index of $1.5$ and an angle $A = 4^o$ is placed in front of a mirror. When the incident ray is reflected by the mirror,what is the total deviation in degrees?

An object is placed at a distance of $15\,cm$ from a convex lens of focal length $10\,cm$. On the other side of the lens,a convex mirror is placed at its focus such that the image formed by the combination coincides with the object itself. The focal length of the convex mirror is.....$cm$

$A$ concave mirror of radius of curvature $h$ is placed at the bottom of a tank containing a liquid of refractive index $\mu$ up to a depth $d$. An object $P$ is placed at a height $h$ above the bottom of the mirror. Outside the liquid,an observer $O$ views the object and its image in the mirror. The apparent distance between these two will be

$A$ convex lens forms an image of an object on a screen. The height of the image is $9 \, cm$. The lens is now displaced until an image is again obtained on the screen. The height of this image is $4 \, cm$. The distance between the object and the screen is $90 \, cm$.

The dispersive power of the material of a lens of focal length $20 \; cm$ is $0.08$. The longitudinal chromatic aberration of the lens is ...... $cm$.

$A$ point object is kept at the first focus of a convex lens. If the lens starts moving towards the right with a constant velocity, the image will