Question

Rays from Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object?

Options

• 15 cm in front of the mirror

• 30 cm in front of the mirror

• between 15 cm and 30 cm in front of the mirror

• more than 30 cm in front of the mirror

Answer 1

30 cm in front of the mirror

Explanation -

The rays from the sun are considered parallel to the principal axis. These rays will converge at the focus of the concave mirror. It shows that focal length of the mirror is 15 cm and the centre of curvature is 30 cm. In case of concave mirror, when the object is placed at the centre of curvature, the image is formed at the centre of curvature itself and of the same size.