Which phenomenon explains why a flat mirror can form an image of objects in front of it?

• A. Reflection
• B. Refraction
• C. Diffraction
• D. Absorption

Answer: (A)

Light reflecting off a smooth surface follows the law of reflection: the incoming ray and the reflected ray make equal angles with the surface normal. In a flat mirror, rays from any point on the object bounce off the surface and travel to your eye. Your brain extends those reflected rays backward in straight lines, so you perceive a point behind the mirror where the rays appear to originate. This creates a virtual image that is the same distance behind the mirror as the object is in front, upright and the same size.

Refraction involves bending light at a boundary between different media, not producing the behind-the-mirror image seen with a plane mirror. Diffraction is the bending and spreading of light around edges, which can blur or pattern light but doesn’t form a clean, accurate image of the object behind a flat surface. Absorption simply turns light into other forms of energy, so no image is formed.