Which device always forms a virtual and small image?

A concave lens always forms a virtual, erect, and diminished image of an object, regardless of where the object is placed. This is because a concave lens is a diverging lens — it spreads out light rays that pass through it, making them appear to come from a point on the same side as the object. The image formed is never real and never magnified.

• Diverging Nature: Concave lens spreads parallel rays outward — refracted rays never actually meet, so image is always virtual
• Always Diminished: The image is always smaller than the object, located between the optical centre and the focus on the same side as the object
• Always Erect: Since the image forms on the same side as the object, it is always upright and never inverted
• Position Independent: Unlike mirrors and convex lenses, the nature of image in a concave lens never changes with object position — always virtual, erect, diminished
• Exam Tip: Concave lens and convex mirror are the only two optical devices that always produce virtual, erect, and diminished images — a must-remember fact for competitive exams