1. Chapter 19 Light, Mirrors, and Lenses Section 1 Properties of Light Pages 550 - 554

2. What is Light? Light is a type of wave that carries energy through matter or space. A source of energy such as the Sun or a light bulb gives off light waves that spread out in all directions from the light source. A light ray is a narrow beam of light that travels in a straight line.

3. Light Travels Through Space Most waves travel through a medium. A Medium is the material through which a wave travels. Light is an electromagnetic wave and doesn’t need a medium in which to travel. Electromagnetic (EM) waves are waves that can travel through empty space or through matter – EM waves travel in – vacuum, air, water, glass, etc

4. Light and Matter Most objects can only be seen if light waves from another source bounce off of them and into your eyes. The process of light striking an object and bouncing off is called reflection. When light waves strike an object, some of the waves are absorbed by the object, some are reflected by it, and some might pass through it. What happens to light when it strikes an object depends on the material the object is made of.

5. Opaque, Translucent, and Transparent All objects reflect and absorb some light waves. Materials are opaque, translucent or transparent depending on how much light passes through them. Which type of material reflects the least amount of light? Transparent Materials

6. Opaque, Translucent, and Transparent Materials that do not let light pass through them are opaque. You cannot see other objects through opaque materials. Some examples include: – Walls – Desks – Most Objects

7. Opaque, Translucent, and Transparent Materials that allow nearly all light that strikes them to pass though are transparent. You can clearly see though these types of object. Some examples include?: Glass and clear plastic.

8. Opaque, Translucent, and Transparent Translucent materials allow only some light to pass through. Although object behind these materials are visible, they are not clear. Some examples include?: Frosted glass and Wax paper.

9. Color The light from the sun may look white, but it is a mixture of colors. Each different color of light is a light wave with a different wavelength. Red light waves have the longest wavelengths and violet light waves have the shortest wavelengths. White light is separated into different colors when it passes through a prism. The colors in white light range from red to violet.

10. Electromagnetic Spectrum

11. Why Do Objects Have Color? When light waves strike an object, some waves are absorbed and some are reflected. If an object reflects red waves and absorbs all the others waves, it looks red. An object that reflects all the light waves that strike it looks white, while one that absorbs all the light waves looks black.

12. Primary Light Colors Light of almost any color can be made by mixing different amounts of the primary colors. The primary colors of light are: red, green, and blue. Different colors are produced where the light beams overlap. For example, you see yellow light when your brain interprets the combination of green and red light.

13. Primary Pigment Colors Materials like paint that are used to change to color of other objects are called pigments. The color of the pigment you see is the color of the light wave that is reflected from it. The primary pigment colors are: yellow, magenta and cyan. You can make almost any color by mixing different amounts of pigments.

14. Primary Pigment Colors Each primary pigment color results when a pigment absorbs a primary light color. For example, magenta pigment absorbs green light and reflects red and blue light.. You see this mixture as the color magenta.