- Discuss and review the Law of Reflection and mixing of colored light

- Investigate the range of visibility of a mirror and practice light ray diagrams

- Extend the Law of Reflection to the formation of images in mirrors

TODAY’S OUTCOMES:BEHAVIOR OF LIGHT

>Give a rule for reflection telling how the directions of the incident and reflected light beams are related

For a light beam on a mirror, the angle of incidence equals the angle of reflection:

angle ofincidence

angle ofreflection

Give a rule for reflection telling how the directions of the incident and reflected light beams are related

For a light beam on a mirror, the angle of incidence equals the angle of reflection:

angle ofincidence

angle ofreflection

Here is a small light source and a mirror. Three light beams are directed towards the mirror. Determine where they are going after they reflect.

Remember - the direction of reflection and the location of images are not the same thing

A common error is to try to place the

beams at 90° angles, because you can

see images ‘off to the side’

WRONGWe will investigate formation ofimages today in class - you will learn WHY you see images “off to the side” using only the Law

of Reflection

Reflection from mirrors at a rightangle

If you measured the angles carefully, you saw that the reflected beam is parallel to the incident beam after 2 reflections.

Reflection of sunlight in a well:

Seeing a reflection of the sun at the bottom of a well is onlypossible if the sun is (almost) directly overhead!

*This observation has a lot to do with the sun and seasons and will be brought up again later...........

This is not the ONLY position the mirror can be in..........

This top view diagram shows a light beam coming straight out from a light station. There is a mirror off to the side not doing anything. You can move the mirror anywhere that you want in the picture. Draw the mirror somewhere in the light beam, showing it turned at the correct angle so that the beam is reflected and goes through the black X. Draw the reflected beam, too.

This top view diagram shows a light beam coming straight out from a light station. There is a mirror off to the side not doing anything. You can move the mirror anywhere that you want in the picture. Draw the mirror somewhere in the light beam, showing it turned at the correct angle so that the beam is reflected and goes through the black X. Draw the reflected beam, too.

This top view diagram shows a light beam coming straight out from a light station. There is a mirror off to the side not doing anything. You can move the mirror anywhere that you want in the picture. Draw the mirror somewhere in the light beam, showing it turned at the correct angle so that the beam is reflected and goes through the black X. Draw the reflected beam, too.

There is no limit to the number of positions the mirror can be in, so long as it is rotated correctly.

- The Law of Reflection: The angle of incidence equals the angle of reflection

- How to trace the path of a light beam reflecting from multiple mirrors

- The “primary colors” of light and how white light can be decomposed into colors

WHAT YOU ARE EXPECTED TO KNOW:

>You observed several different colored light sources using your diffraction grating slide. When you observed light sources that appeared red, green or blue, was the pattern you saw composed of only one color? What does this tell you about these light sources, and color filters in general?

Light sources that we see as one color can, in reality, be composed of many colors in the spectrum. For example, a green light sources contained some red, yellow and blue, as well as green, even though the green portion of the spectrum showed most strongly. Apparently, color filters are not precision instruments; they let through other colors (more weakly), as well.