The linear magnification of a concave lens is always positive, but less than one. This is because:

Lateral displacement on passing through a glass slab depends on:

In case of normal incidence, what would be the angle of deviation through a glass slab:

A student obtains a blurred image of an object on a screen by using a concave mirror. In order to obtain a sharp image on the screen, he will have to shift the mirror:

To obtain a virtual and erect image for any position of the object we need:

A convex lens of focal length $20 \mathrm{cm}$ is placed in contact with a concave lens of focal length $10 \mathrm{cm}$. What is the power of the combination?

For the reflected ray, shown in the diagram draw the corresponding incident ray.