1. Let there be light (and color)!

2. What is Light? Light is a type of Electromagnetic (EM) Energy. Visible light is a small part of the EM spectrum that we can see. We can see a range of wavelengths spanning from approximately 430nm to 790nm.

4. Where does light come from? It all starts with ATOMS A nucleus surrounded by electrons that orbit. Electrons stay in the same orbit unless energy is added to or taken away from the atom. When energy is added, electrons jump to higher orbits.

5. Where does light come from(2) When the atom gives up energy, electrons jump back to original orbits. As they jump back, they emit light in the form of photons. The bigger the jump, the more energy the photon carries. The amount of energy the photon carries determines the color of light produced.

6. Colour White light is not a single colour; it is made up of a mixture of the seven colours of the rainbow. We can demonstrate this by splitting white light with a prism: This is how rainbows are formed: sunlight is “split up” by raindrops.

7. Color of Light (Cont.) Color of Objects –White light is the presence of ALL the colors of the visible spectrum. –Black objects absorb ALL the colors and no light is reflected back. © 2000 Microsoft Clip Gallery

8. Seeing color The color an object appears depends on the colors of light it reflects, all other colors are absorbed. For example, a red book only reflects red light: White light Only red light is reflected

9. A white shirt would reflect all seven colors: A pair of purple pants would reflect purple light (and red and blue, as purple is made up of red and blue): Purple light White light

10. Using colored light If we look at a colored object in colored light we see something different. For example, consider a soccer uniform: White light Shorts look blue Shirt looks red

11. In different colors of light this uniform would look different: The shorts look black because there isn’t any blue light to reflect. Red light Shirt looks red Shorts look black

12. In different colors of light this uniform would look different: The shirt looks black because there isn’t any red light available to reflect. Blue light Shirt looks black Shorts look blue

13. What happens to light when it passes through water? When light strikes a surface it can be affected in a number of ways. When light strikes the surface of water some of it is reflected and some is refracted. Water molecules also tend to scatter blue light but absorb most other colors. Different colors are absorbed at different depths.

14. Light penetration in the ocean The ocean is broken into zones base on how deep light can penetrate. –Euphotic Zone- light intensity allows for photosynthesis. –Disphotic Zone- enough light to see but not enough for photosysthesis. –Aphotic Zone- not enough light to see. –Depths of these zones can vary depending on the clarity of the water and the intensity of the sunlight.

15. The waves can pass through the object The waves can be absorbed by the object. The waves can be reflected off the object. The waves can be scattered off the object. The waves can be refracted through the object.

16. Underwater Light Red, orange and yellow light is absorbed within a few meters of the surface. Green and purple can penetrate a little deeper. Towards the bottom of the Photic Zone only blue light is available. Red and orange animals in deep water look black.

17. The pictures below show the same photograph taken with and without a flash.

18. Marine animals use light and color to communicate.

19. Marine animals use light and color to confuse attackers. Because it is red the shrimp below looks black underwater where there is no red light. Only the blue cloud is visible to the fish.