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Step 1 Identify the top and the bottom of the object (label these “A” and “B”)

for reflections in a plane mirror
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
Attitude (a.k.a. Orientation) Type Inverted Upright Size Real Virtual Laterally Inverted Location Same Enlarged Same side At a particular point (i.e. at C, f<di<2f, etc.) Opposite side Reduced

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 MIRROR MIRROR MIRROR MIRROR
a) Upright - image is right-side up b) Inverted - image is upside-down c) Laterally Inverted - image is flipped horizontally a) MIRROR b) MIRROR MIRROR c) MIRROR

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

Curved Mirrors Concave Convex “converging” mirror “diverging” mirror

Concave Mirrors

Concave Mirrors

Terminology Focal 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 f principal 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 Reflections
5 Cases Object is greater than 2 focal lengths from the mirror (do>2f) – note: 2f = C Object is at 2 focal lengths/Centre of Curvature (2f/C) Object is between 1 and 2 focal lengths from the mirror (f<do<2f) Object is at the focal point (do=f) 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

“Drawing Ray Diagrams for Concave and Convex Mirrors”
Handout p.429 “Drawing Ray Diagrams for Concave and Convex Mirrors”

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