Light

Benchmarks Describe ways in which light interacts with matter. Describe ways in which light interacts with matter. Explain how light is required to see objects. Explain how light is required to see objects.

Misconceptions There are an incredible amount of misconceptions associated with light. 30 are listed here… 30 are listed here… 30 are listed here… Even more misconceptions are associated with color and vision. Another 20 are listed here… Another 20 are listed here… Another 20 are listed here…

Light is energy that travels in waves. When this energy hits an object it may… –Transmitted – passes through –Absorbed – does not pass through –Reflected – bounces off

Transmission of Light If light is being transmitted through something it is somehow passing through it. –It may produce a clear image by having the light pass directly through something that is transparent. –It may produce an unclear image by having the light pass part of the way through something that is translucent. –Or it may produce a broken or bent image by having the light bend or be refracted due to it moving from one media or state of matter to another.

Absorption of Light Different materials Color Video (02:15) Video (02:15)

Reflection of Light Reflection occurs when a light wave strikes an object and bounces off. –Regular reflection- Smooth surfaces reflect light in one direction. (mirror) –Diffuse reflection- Rough surfaces scatter light in many directions. (paper) –See

Angle of Reflection = Angle of Incidence Image irror348.jpg irror348.jpg Mirror348.jpg Animation The Law of Reflection.htm The Law of Reflection.htm

Video Clip…Video Clip… (3:15) Video Clip… Check Your Understanding… – /u13l1c.html /u13l1c.htmlhttp:// /u13l1c.html

Reflection Activities Symmetry and reflection... How can you see more of your body in the mirror? Kaleidoscope Tesselations…. ry/Activity-11.html ry/Activity-11.html ry/Activity-11.html

Light Interacts With Matter Refraction is the bending of waves caused by a change in their speed. It is a type of reflection. –The amount of bending that occurs depends on the speed of light in both materials. –The greater the difference between the speeds of light in two mediums, the more the light is bent as it passes at an angle from one medium to another.

Light Refraction video clips –Refraction.asf Refraction.asf –Wave_Refraction.asf Wave_Refraction.asf –chp6688_300k.asx chp6688_300k.asx –Refracted_Light__Prisms.asf Refracted_Light__Prisms.asf

Light Interacts With Matter In order for you to see an object, it must reflect some light. The type of matter in an object determines the amount of light it absorbs and reflects. –Opaque materials absorb or reflect all light and you cannot see objects through them. (curtains, tables, walls) –Transparent materials allow light to pass through and you can clearly see objects through them. (glass) –Translucent materials allow light to pass through but you cannot clearly see objects through them because the light is scattered. (frosted glass, waxed paper)

Eye Structure & Function

Video

How Light is Required to See Light is a form of energy that moves through space. It is constantly streaming out from light sources in all directions, traveling rapidly through space and bouncing off most objects.

How the Eye Sees Light enters the eye through a hole in the cornea called the pupil and is focused on the retina. Light is then translated into nerve messages that are carried by the optic nerve to the brain.

How the Eye Sees When an object reflects light waves it is said to be illuminated. In order to see these objects, the light waves travel in a straight path and are received by the eye.

How the Eye Sees Color A red sheet of paper appears red because red light is reflected off the paper, while all other colored light (orange, yellow, green, blue, indigo, violet) is absorbed by the paper.

How Light is Required to See Light behaves differently as it interacts with different kinds of matter. In order for one to see objects, light must strike the object and then be reflected from the object to their eyes.

Can You See In the Dark? An object can be seen because of emitted or reflected light. In a “perfectly dark” room, an object cannot be seen because no light is reflected.

There is nothing in the benchmark regarding lenses…..

Color The following 3 screens show still pictures, but look at how they seem to move due to the colors that are used.

Explanation: –Your eyes