Identify the device used as a spherical mirror or lens in the following cases,where the image formed is virtual and erect in each case.
$(a)$ Object is placed between the device and its focus,image formed is enlarged and behind it.
$(b)$ Object is placed between the focus and the device,image formed is enlarged and on the same side as that of the object.
$(c)$ Object is placed between infinity and the device,image formed is diminished and between the focus and optical centre on the same side as that of the object.
$(d)$ Object is placed between infinity and the device,image formed is diminished and between the pole and focus,behind it.

(A-D) Concave mirror: When an object is placed between the pole and the focus of a concave mirror,a virtual,erect,and enlarged image is formed behind the mirror.
$(b)$ Convex lens: When an object is placed between the optical centre and the focus of a convex lens,a virtual,erect,and enlarged image is formed on the same side as the object.
$(c)$ Concave lens: $A$ concave lens always forms a virtual,erect,and diminished image between the optical centre and the focus,regardless of the object's position (between infinity and the lens).
$(d)$ Convex mirror: $A$ convex mirror always forms a virtual,erect,and diminished image between the pole and the focus,behind the mirror,for any object position between infinity and the pole.