J.M. Gabrielse

Ray Diagrams

J.M. Gabrielse

Spherical Mirrors (concave & convex)

J.M. Gabrielse

Concave & Convex (just a part of a sphere)

C: the centre of curvature (centre point of the sphere)

F: the focus (focus) of the mirror (halfway between C and the mirror)

•

C

•

F

Principal Axis

Curved Surface

J.M. Gabrielse

Principal axis

Concave Mirrors (caved in)

•

F

Light rays that come in parallel to the principal axis reflect through the focus.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #1 (image outside C)

•

F

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #1 (image outside C)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #1 (image outside C)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

The second ray comes through the focus and reflects parallel to the principal axis.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #1 (image outside C)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

The second ray comes through the focus and reflects parallel to the principal axis.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #1 (image outside C)

•

F

A image forms where the light rays converge. When we describe the image formed, we

can use the acronym LOST (Location, Orientation, Size, Type).

This image is L - between F and C, O - inverted (upside down from original), S - smaller

than original and T - a real image (on the same side of the mirror).

•

C

J.M. Gabrielse

principal axis

Your Turn - Concave Case #2 (object at C)

•

F

object

concave mirror

• Locate and describe (LOST) the image of the arrow

•

C

J.M. Gabrielse

principal axis

Your Turn - Concave Case #2 (object at C)

•

F object

concave mirror

L - at C, O - inverted, S - same size, T - real

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #3 (image between C and F)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #3 (image between C and F)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.us.

The second ray comes in through the focus and reflects parallel to the principal axis.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #3 (image between C and F)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.us.

The second ray comes in through the focus and reflects parallel to the principal axis.

L - beyond C, O - inverted, S - larger than original, T - real

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #4 (image at F)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #4 (image at F)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.us.

The second ray comes in through the focus but never reflects off the mirror.

Result - NO IMAGE is formed

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #5 (object between F and mirror)

•

F

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #5 (object between F and mirror)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #5 (object between F and mirror)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

The second ray comes through the focus and reflects parallel to the principal axis.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #5 (object between F and mirror)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

The second ray comes through the focus and reflects parallel to the principal axis.

The image forms where the rays converge. But they don’t seem to converge.

•

C

J.M. Gabrielse

principal axis

Concave Mirror Case #5 (object between F and mirror)

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

The second ray comes through the focus and reflects parallel to the principal axis.

The image is L - on the other side of the mirror, O - upright (the same direction as the

original, S - larger than the original, T - virtual (on opposite side of mirror)

•

C

J.M. Gabrielse

Convex Mirrors Case #6 (curved out)

Light rays that come in parallel to the principal axis reflect from the focus.

principal axis

•

F

The focus is considered virtual since sight lines, not light rays, go through it.

•

C

J.M. Gabrielse

Convex Mirrors Case #6 (example)

principal axis

•

F

•

F

•

C

J.M. Gabrielse

Convex Mirrors Case #6 (example)

principal axis

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

•

C

J.M. Gabrielse

Convex Mirrors Case #6 (example)

principal axis

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

The second ray comes through the focus and reflects parallel to the principal axis.

•

F

•

C

J.M. Gabrielse

Convex Mirrors Case #6 (example)

principal axis

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

The second ray comes through the focus and reflects parallel to the principal axis.

The light rays don’t converge, but the sight lines do.

•

F

•

C

J.M. Gabrielse

Convex Mirror Case #6 (example)

principal axis

•

F

The first ray comes in parallel to the principal axis and reflects through the focus.

The second ray comes through the focus and reflects parallel to the principal axis.

The light rays don’t converge, but the sight lines do.

L - other side of mirror, O - upright, S - smaller than original, T - virtual

•

C

J.M. Gabrielse

principal axis

Your Turn (Convex Mirror)

•

C

• Locate the image and describe it

object

convex mirror

•

F

J.M. Gabrielse

principal axis

Your Turn (Convex Mirror)

•

C

L - Other side of mirror, O - upright, S - smaller than original, T - virtual

object

convex mirror

image •

F

J.M. Gabrielse

Thanks/Further Info

• Faulkes Telescope Project: Light & Optics by Sarah Roberts

• Fundamentals of Optics: An Introduction for Beginners by Jenny

Reinhard

• PHET Geometric Optics (Flash Simulator)

• Thin Lens & Mirror (Java Simulator) by Fu-Kwun Hwang