Question

Name the kind of mirror used to obtain a virtual and diminished image.

A. Concave mirror

B. Convex mirror

C. Plane mirror

D. Concave-parabolic mirror

Answer 1

Hint: A highly polished surface, such as a mirror, reflects most of the light falling on it. Let us recall the law of reflection

(i) The angle of incidence is equal to the angle of reflection, and 

(ii) The incident ray, the normal to the mirror at the point of incidence and the reflected ray, all lie in the same plane.

Complete step by step answer:

A spherical mirror whose reflecting surface is curved inwards, that is, faces towards the centre of the sphere, is called a concave mirror. A concave mirror forms a real, inverted and diminished image when the object is placed at the focus. It forms real, inverted and highly enlarged images when the object is placed at infinity. The concave mirror forms a virtual, enlarged and erect image when the object is placed between the focus and the pole. But the concave mirror does not form the virtual and diminished image. Hence, option A is incorrect.

A spherical mirror, whose reflecting surface is curved outwards, is called a convex mirror. When the object is placed between infinity and the pole of the convex mirror, the image formed is virtual, erect and diminished. So, the correct answer is “Option B”.

The image formed by the plane mirror is virtual and of the same size as that of the object. Therefore, the virtual and diminished image is not formed by the plane mirror. Hence, the option C is incorrect.

The images formed by the combination of concave and plane mirror are virtual, erect and enlarged. Therefore, the virtual and diminished image is not formed by the combination of concave and plane mirror. Hence, the option D is incorrect.

Therefore, the correct answer is option B.

Note:
- The images formed by the convex mirrors are always virtual and diminished. 

- The concave mirror does not form a virtual and diminished image.

- A spherical mirror is said to be a convex mirror if its outer side is reflecting.