An object of height 2.5cm is placed at a distance of 15cm from the optical centre ‘O' of a convex lens of focal length 10cm. Draw a ray diagram to find the position and size of the image formed. Mark optical centre ‘O', principal focus F and height of the image on the diagram.

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

Draw ray diagrams showing the image formation by a concave lens when an object is placed:
At the focus of the lens.

Light travels more quickly through water than through glass:

1. Which is optically denser: Water or glass?
2. If a ray of light passes from glass into water, which way will it bend: Towards the normal or away from the normal?

State and explain the laws of refraction of light with the help of a labelled diagram.

‘‘A concave mirror of focal length 15cm can form a magnified erect as well as inverted image of an object placed in front of it.’’ Justify this statement stating the position of the object with respect to the pole of the mirror in both cases for obtaining the images.

Discuss the case when a convex lens forms a virtual and enlarged image.

State and define the S.I. unit of power of a lens.

The diagram given alongside shows a ray of light entering a rectangular block of glass:

1. Copy the diagram and draw the normal at the point of entry.
2. Draw the approximate path of the ray of light through the glass block and out of the other side.

Explain what is meant by a virtual, magnified image.