What are the characteristics of image formed by concave lens?
A concave lens is divergent in nature. As you can see in the figure below, the light rays hit the lens and diverge away from each other. Since diverging rays never intersect, a real image cannot be formed by a concave lens and it always produces a virtual image.
Also, the image formed by a concave lens is always virtual, erect and diminished i.e. smaller in size than the object.