| Feature | Real Image | Virtual Image |
|---|---|---|
| Ray Interaction | Rays physically converge and intersect | Rays diverge and only appear to meet when traced back |
| Projection | Can be captured on a screen | Cannot be projected; only seen by looking through the lens |
| Orientation | Always inverted relative to the object | Always upright (same way up) |
| Lens Type | Formed by convex lenses (object distance ) | Formed by concave lenses or convex (object distance ) |
Precision is Mandatory: Always use a sharp pencil and a ruler. Even a small deviation in the angle of a ray can lead to a significantly incorrect image position or size.
Arrowheads: Ensure every ray has at least one arrowhead to indicate the direction of light travel. Examiners often penalize diagrams with 'directionless' lines.
Virtual Ray Convention: Always use dashed lines for rays that are extended backward (virtual rays) and for the virtual image itself to distinguish them from physical light paths.
Sanity Check: For a convex lens, if the object is closer than , the image MUST be virtual and magnified (magnifying glass effect). If the object is beyond , the image MUST be real and inverted.
Incorrect Refraction Point: Students often bend the ray at the surface of the lens. In the thin-lens approximation, all refraction is drawn as a single bend at the central vertical plane of the lens.
Confusing and : Placing the object at the wrong marker will result in the wrong image characteristics (e.g., getting a diminished image when it should be magnified).
Concave Lens Errors: Forgetting that concave lenses always produce virtual, diminished images regardless of object distance is a frequent conceptual mistake.
