Question

It is given that the image formed by an optical device is virtual, erect and diminished. Image is formed between the focus and optical centre on the same side as that of the object. Object is placed between infinity and device. Identify the device used.

• A. Concave lens
• B. Convex lens
• C. Plane mirror
• D. Spherical mirror

Answer 1

The correct option is A Concave lens

Convex mirror does not form images on the same side of the object, concave mirror never forms erect images on the same side of the object and the image formed by convex lens is not diminished in such case.

When object is placed beyond focal length of a concave lens as shown in the diagram, image formed is virtual, diminished and on the same side of the lens as object.

It can hence be concluded that device must be concave lens.