Mirrors and Lens

Mirrors

There are 3 types of mirror a plane mirror, concave/converging mirror, and a convex/diverging mirror.

Plane Mirrors

**Flat reflective surface**

Plane MirrorRay Diagram for Plane Mirrors

1. Choose about 4 points on the object

2. From each point draw a perpendicular line to the mirror

3. Draw another perpendicular line of equal distance behind the mirror (dashed line)

4. Draw the Image point

Concave Mirror

Concave-Mirror

Concave Mirror – mirror shaped like a sphere where two inner surface is reflective, light rays converge inward.

Terminology

Center of Curvature – (c) – the center of the sphere

Principal Axis (PA) – line through the center of curvature to the midpoint of the mirror, the “normal” 90

Vertex (v) – middle point of mirror

Focal Point (f) – midpoint between C and V

Locating an Image in Concave Mirror

1. Draw the first ray from the top of the object to the mirror parallel to PA

2. Reflect the ray back from the mirror through F

3. Draw the second ray from they top of the object through F

4. Reflect the ray back from the mirror parallel to the PA ; Draw the image where the 2 rays

Convex Mirrors

Convex_mirror

Convex Mirrors – shaped like a sphere where the outer surface is reflective, light rays diverge outward

**Virtual Focus – midpoint between C and V located behind the mirror**

Locating an Image in a Convex Mirror

1) Draw the first ray from the top of the object to the mirror, parallel to PA

2) Reflect the ray back, it will appear to have originated from F

3) Draw the second ray from the top of the object towards F

4) Reflected the ray back from the mirror, parallel to PA ; Draw the virtual image where the rays appear to intersect

Lens

There are two types of lens Convex/Diverging and Concave/Converging.

Convex

  • thickest in middle
  • causes incident parallel rays converging through a sigle point after refraction

Locating the Image in a Convex Ray

1. Draw the first ray from they top of the object to the lens parallel to the PA, nd refract it through the lens through F.

2. Draw the second ray from the top of the object through F; and refract it parallel to the PA

3. Draw the third ray from the top of the object through O; draw the image where the three rays intersect

Concave

  • thinnest in middle
  • cause incident parallel light rays to spread apart after refractin so it appears as if they ome from a virtual point

Locating the Image in a Convex Ray

1. Draw the first ray from the top of the object to the lens. parallel to the PA, and refract it as though it had come from F

2. Draw the second ray from the top if the object as though it passes through F ; and refract it parallel to the PA

3. Draw the third ray through O ; Draw the image where the three rays appear to intersect

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