Draw ray diagrams for the cases of images obtained in concave mirrors as described in the table on page 122.

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Solution

I. When the object is at infinity

The light rays coming from infinity are parallel. When parallel light rays are incident on the reflecting surface of a concave mirror, they tend to meet at its focus after reflection. In this case, the image is formed at the focus, and is point-sized.

II. When the object is behind the centre of curvature

In this case, the image is formed between the focus (F) and the centre of curvature (C). This image is real, inverted and diminished.

III. When the object is at the centre of curvature

In this case, the image is formed at the centre of curvature. This image is real, inverted and of the same size as the object.

IV. When the object is between the centre of curvature (C) and the focus (F)

In this case, the image is formed behind the centre of curvature. This image is real, inverted and magnified.

V. When the object is at the focus (F)

In this case, the image is formed at infinity. This image is real, inverted and highly enlarged.

VI. When the object is placed between the focus (F) and the pole (P)

In this case, the image is formed behind the mirror. This image is virtual, erect and magnified.

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