Question

Can we obtain an image twice the size of the object using a concave lens?

Answer 1

No. A concave lens cannot produce an image that is twice the size of the object.

A concave lens always forms a virtual, erect (upright), and diminished (smaller than the object) image. The image is formed between the optical center and the principal focus on the same side of the lens as the object.

Therefore, a concave lens cannot produce a magnified image (such as one that is twice the size of the object).