Draw ray diagrams showing the image formation by a concave mirror when an object is placed:
At centre of curvature of the mirror.

A convex lens of power 5D and a concave lens of power 7.5D are placed in contact with each other. What is the:

1. Power of this combination of lenses?
2. Focal length of this combination of lenses?

When an object is placed at a distance of 36cm from a convex lens, an image of the same size as the object is formed. What will be the nature of image formed when the object is placed at a distance of:

1. 10cm from the lens?
2. 20cm from the lens?

A lens has a focal length of, -10cm. What is the power of the lens and what is its nature?

Identify the device used as a spherical mirror or lens in following cases, when the image formed is virtual and erect in each case.Object is placed between infinity and device, image formed is diminished and between pole and focus, behind it.

Draw a ray diagram to show the path of the reflected ray corresponding to an incident ray which is directed towards the principal focus of a convex. mirror. Mark on it the angle of incidence and the angle of reflection.

Write down the magnification formula for a lens in terms of object distance and image distance. How does this magnification formula for a lens differ from the corresponding formula for a mirror?

The boy walks towards the mirror at a speed of 1m/ s. At what speed does his image approach him?

An object lies at a distance of 2f from a concave lens of focal length f. Draw a ray-diagram to illustrate the image formation.

The focal length of a lens is +150mm. What kind of lens is it and what is its power?