Images in Plane Mirrors

Characteristics of Plane Mirrors

  • A plane mirror is a standard, flat wall mirror.

  • Image formation is determined by light rays and the laws of reflection.

  • While a light source radiates rays in all directions, only those that strike the mirror and reflect into the eyes are used to perceive an image.

Perception and Virtual Images

  • Light travels in straight lines; when the eyes detect reflected light, the brain projects these rays directly back into the mirror.

  • This projection leads the brain to perceive a light source behind the mirror.

  • This phenomenon creates a "Virtual Image," which is an image located where no actual light source exists.

S.A.L.T. Classification Method

The properties of an image are described using the S.A.L.T. acronym:

  • S: Size (Same size, smaller, or larger).

  • A: Attitude (Upright or inverted).

  • L: Location (Placement relative to the mirror or lens).

  • T: Type (Virtual or real).

Constant Properties of Plane Mirror Images

Images formed in plane mirrors always maintain the following characteristics:

  • Size: Same size as the object.

  • Attitude: Upright.

  • Location: Behind the mirror, at the same distance as the object is from the mirror.

  • Type: Virtual.

Drawing Ray Diagrams for Plane Mirrors

To locate an image, you must use a minimum of 22 points from each extremity of the object and follow these steps:

  • 1.1. Draw an incident ray from the object to the mirror surface.

  • 2.2. Measure the angle of incidence using a protractor; this also identifies the angle of reflection.

  • 3.3. Draw the reflected ray.

  • 4.4. Extend the reflected ray backwards behind the mirror using a dotted line.

  • 5.5. Repeat these steps for at least a second point at the same extremity, and then for the other extremities of the object.