1. Laws of Reflection and Plane Mirror Images

2. Reflection
When light strikes a surface, some is absorbed, the rest bounces off the surface. This is called reflection.

3. Reflection on Different Surfaces
When the reflecting surface is rough, it produces a diffuse reflection.

4. Reflection on Different Surfaces
When the reflecting surface is smooth, it produces a specular (uniform) reflection.

5. Reflecting Light Terms
Incident Ray: Approaching ray
Reflected Ray: Ray that the mirror reflects
Point of Incidence: Place where incident ray strikes a mirror.
Normal: Line at right angles to the surface of the mirror drawn at the point of incidence

6. Plane Mirror Incident Ray Normal Reflected Ray Plane Mirror
Point of Incidence
Reflected Ray

7. Reflecting Light Terms (cont.)
Angle of Incidence (θi): Angle between the Incident Ray and the Normal
Angle of Reflection (θr): Angle between the Reflected Ray and the Normal

8. Plane Mirror Incident Ray Angle of Incidence Angle of Reflection
Reflected Ray

9. Laws of Reflection
The Angle of Incidence is equal to the Angle of Reflection (θi = θr)
The Incident Ray, the Reflected Ray and the Normal all lie in the same plane.

10. Images in a Flat Mirror
An illuminated object gives off light in all directions, but you see only the rays coming toward you.

11. Flat or Plane Mirror
Reflected object appears to be coming from the other side of the mirror.

12. Your brain does not process the fact that light has been reflected
Assumes that light travels in a straight line.
Assumes the origin of the rays is behind the mirror.

13. Image Characteristics of a Plane Mirror (SALT)
Size: No magnification
Attitude: (Orientation) Laterally inverted (left-right inverted)
Location: Image distance is same as object distance
Type: Image is virtual (cannot be focused on a screen)

14. Ray Diagrams A way to locate a virtual image do = object distance
di = image distance
For a plane mirror: do= di

15. Image Characteristics of a Plane Mirror (SALT)
S: size of image
a size comparison between the height of the image (hi) and the height of the object (ho) M = hi / ho = di / do
A: attitude (orientation) of image – upright or inverted
L: location of image (distance to the mirror)
T: type of image (real or virtual)
Virtual images are formed in locations where light does not actually reach
Real images can be projected on a screen

16. Mirror image is laterally inverted.
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