Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 19 Light, Mirrors, and Lenses Section 1 Properties of Light Pages 550 - 554 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. 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 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. 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 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 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. 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. 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. Electromagnetic Spectrum 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. 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. 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. 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.