NAME: Period: DATE H. Physics Nature of Light What is Light? Goal . Explain and describe the nature of light? Use the following linked reference: What is Light? Videos on the Nature of Light Another Video What to Do Use the terms at the beginning of each section to complete the sentences that follow. Fluorescence efficient electrical expensive fluorescent hot incandescent phosphor poisonous ultraviolet vapor visible 1. The long tubes in overhead lights and the tubes that spell the names of stores and restaurants are examples of light sources. They do not work the same way as bulbs, which have filaments that heat up and glow. 2. In fluorescent bulbs, energy is absorbed by the particles of mercury _inside the tube. These particles give off light (a type of light you cannot see), which hits the white powder on the inside of the bulb. The phosphor particles give off light. 3. A disadvantage of these bulbs is that they are , so their contents are An advantage of these bulbs is that they are energy because they do not get Phosphorescence delay energy glows light 4. Phosphorescence is similar to fluorescence, except the particles that absorb the do not release it immediately. There is a_ . An example is a toy ball that after you hold it near a bright for a while. Chemiluminescence and Bioluminescence artificial chemical light living 5. Electrical and solar energy are used to make incandescent or fluorescent light. Energy released in _reactions provides the energy for chemiluminescence and bioluminescence, Chemiluminescence refers to light produced this way, Bioluminescence refers to the produced by organisms.Period: DATE: NAME: H. Physics PROBLEM SOLVING Turn Off That Light! Goal . Calculate the cost of electricity. Think About It Have you ever been told to turn off the lights in your room when you leave? This is because energy costs money. We have to pay for the gasoline needed to drive a car, and for the electricity used by our lights and appliances. The cost of electricity varies. In rural areas, electricity often costs more than it does in cities because the electric companies have to use longer wires to service fewer people. Businesses, industries, and homes are charged different rates. How much do you think it costs to use electricity? Complete this worksheet to find out. What to Do Answer the following questions in the space provided. Assume that electricity costs 8/kW-h. This means that if a 1000 W appliance is left on for 1 h, it uses 8e worth of electricity. Cost = number of kilowatts x number of hours x 8 = number of watts + 1000 x number of hours x 8 1. What is the cost of electricity in each situation? Show your work. (a) A 100 W light bulb is left on from 10:00 at night to 7:00 the next morning. (b) A turkey takes 3 h to cook in a 1500 W oven. (c) You watch a 500 W television set for 7 h. Going Further 1. Lee's family has a summer cottage that they usually close up for the winter. One year, they closed up the cottage on October 8. When they returned the next year, on May 22, they discovered that they had left a 1 kW heater on. Assuming that the heater ran about half the time, approximately how much did this little mistake add to their electricity bill?ASSESSMENT When Light Strikes Goal . Classify various materials as transparent, opaque, or translucent, and describe the behavior of light when it strikes different materials. What to Do Answer the following questions in the space provided or on a separate page. 1. What does a sharp shadow tell us about the way light travels? 2. Describe how light is affected by (a) a transparent object (b) an opaque object (c) a translucent object 3. Why is frosted glass often used for bathroom windows instead of clear glass or a solid wall? 4. Complete the table below. In the second column, classify each material as transparent, opaque, or translucent. In the third column, state whether light is absorbed, reflected, transmitted, or scattered when it strikes the material. In the last two boxes of the first column, write your own examples. Material Classification Behavior of light glass white clouds stained glass window aluminum foil fog cellophane cardboard wax paper black chalkboard mirror transparent scattered