Evans SPH 3U1

Physics Grade 11

Unit 3: Light and Optics

Note 3: Curved Mirrors

Reference: Chapter 10.7

Terminology (show with diagram):

Concave/Convex

C, Centre of curvature

F, Focal point

V, vertex

f, Focal length (=FV)

R, Radius of curvature

PA, Principal axis

CA, Secondary Axis

Rules for Drawing Images in Concave (converging) Mirrors:

1) Draw a reference line (principal axis)

2) Light rays parallel coming in parallel to the principal axis will reflect through the focal point, F.

3) Light rays incident on the vertex obey (the principal axis acts as a normal)

4) Light rays passing through the focal  point will be reflected parallel to the principal axis.

Note: 2) and 4) only work near the principal axis.

Show overheads Fig. 10.35, 10.36

On overhead Show Example of Real, Inverted, Smaller Image

Discuss and students should understand (not memorize) Fig. 10.37 and 10.38 (discuss - location, type, size, attitude)

Rules for Drawing Images in Convex (diverging) Mirrors: (same rules with minor modifications)

1) Draw a reference line (principal axis)

2) Light rays parallel coming in parallel to the principal axis will appear to emerge from the focal point, F.

3) Light rays incident on the vertex obey (the principal axis acts as a normal)

4) Light rays coming in through the focal  point will be reflected parallel to the principal axis.

Note: 2) and 4) only work near the principal axis.

On overhead Show example

Show overheads Fig. 10.39, 10.40

Complete exercise on "Locating An Image In a Concave/Convex Mirror"

Read 10.9

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