step 1 identify the top and the bottom of the object (label these “a” and “b”)

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”