Question

which of the following diagrams involves a virtual image?

Explanation:

Step1: Recall virtual image formation

A virtual image is formed when light rays appear to diverge from a point, and the image cannot be projected on a screen. For convex lenses, a virtual image is formed when the object is within the focal length ($u < f$), and the image is upright, magnified, and on the same side as the object (formed by extending diverging rays backward).

Step2: Analyze each diagram

• First diagram: Light rays converge to a real image (on the opposite side of the lens, can be projected), so real image.
• Second diagram: Light rays converge to a real image (opposite side, projectable), real image.
• Third diagram: Light rays diverge after passing through the lens, and the image is formed by extending the diverging rays backward (dashed lines), on the same side as the object, upright – this matches virtual image formation (object within focal length for convex lens, image is virtual).

Answer:

The third diagram (with dashed lines for image formation, object within focal length, image on the same side as object) involves a virtual image.