1. Ray Diagrams Basics Mirror Equations
Curved Mirrors
Ray Diagrams
Basics
Mirror Equations

2. Concave Mirrors Focal point is …
½ way between Center (Radius) of Curvature & Mirror
in front of the mirror

3. Ray Diagrams for Concave Mirrors
Parallel Ray
Start from top of object
Goes parallel to axis & hits mirror
Reflects off mirror through focal point.
Image is:
Smaller
Inverted
Real
Focal Ray
Start from top of object
Goes through focal point & hits mirror
Reflects off mirror parallel to axis
Center Ray
Start from top of object
Goes through center of curvature
Reflects off mirror back through center
Image
Top of the Image is formed at intersection of the three rays
Bottom is on the axis

4. Convex Mirrors Focal point is…
½ way between Center (Radius) of Curvature & Mirror
behind the mirror

5. Ray Diagrams for Convex Mirrors
Parallel Ray
Start from top of object
Goes parallel to axis & hits mirror
Reflects off mirror lined up with focal pt.
Focal Ray
Start from top of object
Aimed at focal point & hits mirror
Reflects off mirror parallel to axis
Center Ray
Start from top of object
Goes through center of curvature
Reflects off mirror back through center
Image
Three Rays do not meet in the “Real World”
Trace reflections back into “Mirror (Virtual) World”
Image formed at intersection of rays in “Mirror World”
Image is:
Smaller
Upright
Virtual

6. Mirror Equations Mirror Equations: (1/do)+ (1/di) = (1/f) C = 2f
f is positive for Concave mirrors
f is negative for Convex mirrors
di is positive for Real images (in front of Mirror)
di is negative for Virtual Images (Behind Mirror)
C = 2f
Magnification (Hi, Ho, Di, Do its off to physics we go…)
(hi/ho) = - (di/do) = M

7. Di/Do f Hi M + in front of mirror + in front of mirror - behind mirror
+ upright
- inverted M f
+ in front of mirror
- behind mirror

8. Objects and Images @ infinity
On object on the horizon… i.e. the sun
Is very far away
Assume do = ∞
1/do = 1/∞ = 0
Images at infinity
1/di = 1/∞ = 0

9. Concave Mirrors Practice
(1/do)+ (1/di) = (1/f)
(1/21)+ (1/di) = (1/7)
1/di = 0.095
di = 10.5
hi/ho = - di/do = M
hi/6 = 10.5/21 = M
M = - 0.5
hi = - 3 cm
Image is:
Smaller
Inverted
Real
6 cm
21 cm
14 cm

10. Homework
Pg. 659 #7 & 8
Ray Diagram Worksheet