1. How can you bend light away from the normal?
2. How must light travel out of a substance if it is not going to be refracted?

When a light ray passes from air into glass, what happens to its speed? Draw a diagram to show which way the ray of light bends.

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.

A doctor has prescribed a corrective lens of power, -1.5D. Find the focal length of the lens. Is the prescribed lens diverging or converging?

Explain with the help of a diagram, why the convex lens is also called a converging lens.

An extended object in the form of an arrow pointing upward has been placed in front of plane mirror. Draw a labelled ray-diagram to show the formation of its image.

Draw ray diagrams showing the image formation by a convex mirror when an object is placed:
At finite distance from the mirror.

Draw ray diagrams showing the image formation by a convex lens when an object is placed:Between focus and twice the focal length of the lens.

To find the image distance for varying object distances in case of a convex lens of focal length 15 cm, a student obtains on a screen a sharp image of a bright object by placing it at 20 cm distance from the lens. After that he gradually moves the object away from the lens and each time focuses the image on the screen.

1. In which direction-towards or away from the lens does he move the screen to focus the object?
2. How does the size of image change?
3. Approximately at what distance does he obtain the image of magnification -1?
4. How does the intensity of image change as the object moves farther and farther away from the lens?