2. air water As light reaches the boundary between two media,
it’s energy is partially reflected back and
partially transmitted into the new medium.
The amount that is reflected
depends on the types of materials and
the angle of incident rays.
air
water

3. Types of Reflection Diffuse: Rough Surfaces
Ex: paper, cloth or unpolished wood
Specular Reflection: Smooth, shiny surfaces
Ex: mirrors, water

4. Law of Reflection
A line drawn perpendicular to the reflecting surface is called the normal.
Angle of incidence: angle between incoming ray and the normal (θi)
Angle of reflection: angle between reflected ray and the normal (θr)
1st Law: Incident and reflected angles are equal.
θ θr’ θ θi

5. Concept Check
Click for Answer

6. Images formed by mirrors and lenses
may be classified as real or virtual.
Real Image
formed by actual rays of converging light
Virtual Image
Images formed where light does not actually reach, but from where the rays of light appear to diverge (behind the mirror or in front of the lens)

7. Plane Mirror Images 1. Virtual (behind the mirror) 2. Upright
Images formed by plane mirrors are always:
1. Virtual (behind the mirror)
2. Upright
3. Same size as the object
4. Left and right are reversed
5. Located the same distance from the mirror as the object

8. Concept Check
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10. Concept Check
Click for Answer

11. Curved Mirror Math Mirror Equation f = focal length
f = focal length
(+) converging mirror (concave)
(-) diverging mirror (convex)
do = object distance
di = image distance
(+): In front of mirror
(-): Behind mirror

12. Practice Problem
A 5.0 cm tall virtual image is produced by a concave mirror with a focal length of 6.0 cm. If the image appears to be 3.0 cm from the mirror, what is the location of the object?

13. Curved Mirror Math Magnification ho = object size (height)
ho = object size (height)
hi = image size (height)
(+): Upright
(-): Inverted
do = object distance
di = image distance
(+): In front of mirror
(-): Behind mirror

14. Practice Problem
A 5.0 cm tall virtual image is produced by a concave mirror with a focal length of 6.0 cm. If the image appears to be 3.0 cm from the mirror, what is the height of the object?

15. Spherical Aberration
Light rays far from the principle axis of a mirror will not converge to the exact same point, making the image blurry.
Spherical aberration can be reduced using parabolic mirrors.