step 1 identify the top and the bottom of the object (label these “a” and “b”)
TRANSCRIPT
Step 1
• Identify the top and the bottom of the object (label these “A” and “B”)
Ray Diagrams
for reflections in a plane mirror
Step 2
• Draw a line from point A that is perpendicular to the mirror
Step 3• Draw an incident ray
(starting at point A)• Draw a “normal” where
the incident ray hits the mirror
• Use a protractor to draw a reflecting ray
(Remember that i = r )
Step 4
• Extend line A to point Ai (equidistant from point A on the other side of the mirror)
• Connect point Ai to your reflection ray
Step 5
• Repeat steps 2-4 for Point B
Try it!
Reflection Characteristics
Type
Size
Attitude (a.k.a. Orientation)
Real Virtual
Enlarged
Reduced
Same
Upright
Laterally Inverted
Inverted
Location
Same side
Opposite side
At a particular point (i.e. at C, f<di<2f, etc.)
Type• Real - image appears in front of the mirror
(could be projected onto a screen)
• Virtual - image appears behind the mirror
Size
a) Enlarged - image is larger than the object
b) Reduced - image is smaller than the object
c) Same - image is the same size as the object
a)
b)
c)
Attitude
a) Upright - image is right-side up
b) Inverted - image is upside-down
c) Laterally Inverted - image is flipped horizontally
a)
b)
c)
Location
• Image is located on the same side of the mirror
• Image is located on the opposite side of the mirror
• Image can also be located at a specific point (e.g. at centre of curvature, f<di<2f, etc.)– Note: image location will always be
di=do for plane mirrors
Curved Mirrors
Concave Convex
“converging” mirror “diverging” mirror
Concave Mirrors
Concave Mirrors
TerminologyFocal Point (F) - where the light rays meet
Vertex - the middle point of a curved mirror
Focal Length (f) - the distance from the focal point to the vertex
vertex
fprincipal axis
Concave Mirror Ray Diagrams
Ray 1 - travels parallel to the principal axis and reflects through the focal point (F)
Concave Mirror Ray Diagrams
Ray 2 - travels through the focal point and reflects parallel to the principal axis
Concave Mirror Ray Diagrams
The point where the two reflected rays converge will be the location of the image
Concave Mirror Ray Diagrams
• A third ray (shown in red) should be drawn as a “check”
• This can only be used if the Centre of Curvature (“C”) is present in the diagram – which is usually 2X focal length.
You try!
• Turn your notes over• There are 5 “cases”
Concave Mirror Reflections5 Cases1. Object is greater than 2 focal lengths from
the mirror (do>2f) – note: 2f = C2. Object is at 2 focal lengths/Centre of
Curvature (2f/C)3. Object is between 1 and 2 focal lengths
from the mirror (f<do<2f)
4. Object is at the focal point (do=f)5. Object is between the mirror and the focal
point (V<do<f)
Case 1: Object beyond 2f/C
Type Size Attitude
Real Reduced
Inverted
Case 2: Object at 2f/C
Type Size Attitude
Real Same Inverted
Case 3: Object between 2f and F
Type Size Attitude
Real Enlarged
Inverted
Case 4: Object at F
Type Size Attitude
No Image Formed!
Case 5: Object between F and V
Type Size Attitude
Virtual Enlarged
Upright
Handout p.429“Drawing Ray Diagrams for
Concave and Convex Mirrors”