Concave/Convex Mirror Image Formation Rules

1. Parallel Rays - Light rays parallel to the principal axis are reflected through the focus of the mirror.

2. Focus Rays - Light rays through the focus of the mirror are reflected parallel to the principal axis.

3. Chief Rays – Light rays through the center of curvature of the mirror are reflected back along the same path.

4. Vertex Rays – Light rays that strike the mirror at its vertex leave at the same angle that it entered.

1

2

1

2

4

4

3

3

fC

Object Located Beyond f and C.

object

image

fCobject

image

Concave Mirror Image Formation for an Object Less than f

1

2

3

4

Convex Mirror Image Formation

f C

1

2

3

4

objectimage

Concave Mirror Image Formation

• Concave Mirror Beyond C

• Concave Mirror Between C and f

• Concave Mirror Image Formation Less than f

Lenses

The focal length for a lens is dependent on both the curvature of the lens, and the lens material.

Convex Lens (Converging Lens)

f

All light rays parallel to the principal axis converge to the focal point after passing through the convex lens.

Image PropertiesImage Type: Real or VirtualImage Orientation: Inverted or ErectImage Height (Size): Smaller, Larger, SameImage Distance: Closer, Farther, Same

•The image properties of a convex lens are the same as a concave mirror.

Concave Lens (Diverging Lens)

The light rays parallel to the principal axis refract and diverge after goingthrough the lens, such that if the refracted light rays are extended backwards, then the rays would converge at the focal point for the lens.

Image PropertiesImage Type: VirtualImage Orientation: ErectImage Size: SmallerImage Distance: Closer

• The image properties of a concave lens are the same as a convex mirror.

f

Lens Ray Image Formation Rules

1. Parallel Ray – A light ray parallel to the principal axis is refracted towards the lens focus.

2. Focal Ray - A light ray passing through the focus refracts parallel to the principal axis.

3. Chief Ray – A light passing through the center of the lens continues traveling along its original path unaffected by the lens.

Convex Lens Ray Diagram(Beyond f)

f2f f 2f

1

2 3

3

1

2

object

image

Convex Lens Ray Diagram(Less than f)

f2f f2f

1 1

object

image

3

22

Concave Lens Ray Diagram

f f2f 2f

object

image

11

3

22

3

fC

When do=∞, di=f, hi<<ho,real

When do=C,di=C, hi=ho, real

object C>do>f, do>C, hi>ho, real

do from ∞

image

do=f, di=∞,no image

When do<f, di>do, hi>ho,virtual

Image Properties Graphic (Converging Instruments)

Convex Mirror Image Formation

f Cobjectimage

do<∞,di<f,hi<ho,virtual

do=∞,di=f,hi<<ho,virtual

Concave Lens Ray Diagram

f f2f 2fdo=∞,di=f,hi<<ho,virtual

do<∞,di<f,hi<ho,virtual

object

image