1. 18.2 Reflection and MirrorsPg

2. Reflection of Light Rays
The reflection you see in the mirror depends on how the surface reflects the light
Rays are straight lined representations of how light reflects
Light rays obey the law of reflection
The two ways in which a surface can reflect light are regular reflection and diffuse reflection

3. Regular Reflection
When parallel rays of light hit a smooth surface, regular reflection occurs
All the light rays reflect at the same angle
Produces a sharp reflection

4. Diffuse Reflection
When parallel rays of light hit a bumpy or uneven surface, diffuse reflections occur
Light rays hit the surface at different angles because of the uneven surface
Each light ray reflects at a different angle
DO NOT see a clear reflection

6. Plane Mirrors
Plane mirrors are a flat sheet of glass, that has a silver-colored coating on one side
the coating reflects the light
The coating is smooth = regular reflection occurs and a clear image forms
Image is a copy of an object formed by reflected or refracted rays of light

7. What kind of image forms:
Virtual images are upright images that forms where light seems to come from
Virtual = something that does not really exist
Plane mirrors produce virtual images that are upright and the same size as the object
Image not exactly same as object
The left and right of the image are reversed

8. How Images Form
Light rays from the object strike the mirror and reflect towards the observer’s eye
Even though rays are reflected the observer’s brain treats them as if they had come from behind the mirror
Image appears to be behind the mirror

9. Concave Mirrors
A mirror with a surface that curves inward like the inside of a bowl is a concave mirror
Reflects parallel rays of light so that they meet at a point
The Optical Axis is an imaginary line that divides a mirror in half
The Focal Point is the point at which rays parallel to the optical axis meet
Depends on shape of mirror
More curved the mirror the closer the focal point is to the mirror

10. Concave Mirrors
The Optical Axis is an imaginary line that divides a mirror in half
The Focal Point is the point at which rays parallel to the optical axis meet
Depends on shape of mirror
More curved the mirror the closer the focal point is to the mirror

11. X= Focal Point ---- = Optical Axis

12. Representing How Images Form
Ray diagrams are used to show where a focused image forms on a concave mirror
Shows rays of light coming from points on the object
Two rays coming from one point on the object meet or appear to meet at the corresponding point on the image
***Turn to pg. 620 to practice drawing ray diagrams***

13. Determining the Type of Image
Concave mirrors can form virtual or real images
If an object is placed at the focal point = NO Image forms!
if the light is placed at the focal point it can project parallel rays of light
Ex. Car headlights

14. Real Vs. Virtual Images Real images form when rays actually meet
Occur if the object is farther away from the mirror than the focal point
May by larger or small than the object
Virtual images form when the object is between the mirror and focal point
are always larger than the object for concave mirrors

15. Convex Mirrors
Convex Mirrors are mirrors with surfaces that curve outwards
rays spread out but appear to come to from a focal point behind the mirror
Because rays never meet, images formed by convex mirrors are always virtual and smaller than the object
Used in car mirrors
Advantage: allows you to see a larger area than you can with a plane mirror
Disadvantage: images appears further away than it really is