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

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.

A 4 cm tall object is placed on the principal axis of a convex lens. The distance of the object from the optical centre of the lens is 12cm and its sharp image is formed at a distance of 24cm from it on a screen on the other side of the lens. If the object is now moved a little away from the lens, in which way (towards the lens or away from the lens) will he have to move the screen to get a sharp image of the object on it again? How will the magnification of the image be affected?

Describe the nature of image formed when the object is placed at a distance of 20cm from a concave mirror of focal length 10cm.

A ray of light is incident on a convex mirror as shown. Redraw the diagram and complete the path of this ray after reflection from the mirror. Mark angle of incidence and angle of reflection on it.

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

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

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

A student focuses the image of a well illuminated distant object on a screen using a convex lens. After that he gradually moves the object towards the lens and each time focuses its image on the screen by adjusting the lens.

1. In which direction-towards the screen or away from the screen, does he move the lens?
2. What happens to the size of the image-does it decrease or increase?
3. What happens to the image on the screen when he moves the object very close to the lens?