Reflection — Real and Virtual Images
Reflection is the process by which light bounces off a surface following definite rules. All reflective phenomena obey the laws of reflection.
Laws of Reflection
- The angle of incidence (i) equals the angle of reflection (r):
∠i = ∠r. - The incident ray, the reflected ray and the normal all lie in the same plane.
Image Formation in a Plane Mirror
- The image is virtual because the reflected rays only appear to meet behind the mirror — they don’t actually intersect.
- The image is the same size as the object and at the same distance behind the mirror as the object is in front.
- It is laterally inverted — the right side of the object appears on the left of its image.
Types of Reflection
| Type of Reflection | Surface Condition | Ray Behaviour | Examples |
|---|---|---|---|
| Regular Reflection | Very smooth and polished surface. | Reflected rays remain parallel. | Plane mirror, still water, polished metal, glass. |
| Irregular (Diffuse) Reflection | Uneven or rough surface. | Reflected rays scatter in many directions. | Wooden table, walls, blankets, rough ground. |
Real and Virtual Images — Comparison
| Property | Real Image | Virtual Image |
|---|---|---|
| Formation | Formed when reflected rays actually meet. | Formed when reflected rays appear to meet behind the mirror. |
| Screen Capture | Can be formed on a screen. | Cannot be formed on a screen. |
| Nature of Image | Always inverted. | Always upright. |
| Examples | Image on a cinema screen, retina of eye. | Image in a plane mirror, magnifying glass. |
Exam Tips
- Remember: ∠i = ∠r always, even for rough surfaces (scattered rays still obey law individually).
- Virtual images cannot be projected onto a screen because the rays do not actually converge.
- Lateral inversion → “right becomes left.” Your writing appears reversed in a mirror.
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