CHAPTER 7 What are the characteristics of light, sound.pptx

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1. What are the characteristics of light, sound, and heat?

2. Watching a show in a giant theater is fun. Loud sound are used to catch attention of the audience and lights are used to focus the audience’s attention to the performers. The lights in a theater are so intense that spectators in the front row can feel their heat. Light, sound, and heat are all forms of energy.

3. Have you ever played “Pin the Tail on the Donkey” before? Have you experience a brownout at home at night? What difficulities related to this did you have? Without light you cannot see; thus, you will not be abke to do what what you need to do or go to where you want to go.

4. Characteristics of light Light makes you see the things around you. Without light, you cannot see objects at night or the beauty of the world in the morning. Everything will be dark. Can you imagine how boring life would be without light?

5. Light is a form of energy. It travels very fast. In space, it travels about 300, 000, 000 meters per second. It is bright during the day because the light from the sun reaches us. What about during the night? So how does light travel? What happens when light strikes an object?

6. Travel in a straight light Light a candle and let it stand on the table. Then, with one eye closed, look through a drinking straw or tube so you can see the candle flame. Now bend the straw or tube in the middle. Can you still see the flame?

7. Light travels in a straight line. It cannot bend around a corner. This is why you did not see the flame when the straw was bent. The inability of light to bend around a corner is the reason why we have night and day. It is daytime on the side of the earth that is facing the sun because it is directly hit by the light from the sun. The other side is a night time because it receives no light from the sun. What do you think will happen if the light from the sun is able to bend and travel to the other side of the earth?

8. Travels in all directions Have you heard about “blind corners?” why do you think are they called us such? When crossing a blind corner, what precaution should you observe? Aside from traveling in a straight line, light also travels in all directions. For instance, when you turn on the light in a dark room, the whole room is lit up.

9. Do all materials allow light to pass through them? Turn on flashlight and hold various objects in front of the light. Which objects allowed light to pass through them?

10. transparent Objects that allow almost all of the light to pass through them are called transparent materials. Clear glass is a transparent material. What other transparent materials did you know?

11. translucent Some materials like tinted glass allow only some of the light to pass through them. Thus, you can only see a blurred image of what is on their other side. These materials are called translucent materials. Example of translucent materials are wax paper, frosted glass and colored tracing paper.

12. reflection Lay a mirror flat on the floor. Focus the beam from a flashlight at an angle on a mirror. Can you see the bright spot on the wall? The bright spot is actually the light from the flashlight that hit the mirror and bounced off it. We say that light has been reflected by the mirror. Reflection is the bouncing of light as it strikes a surface. It is similar to the bouncing of a rubber ball when dropped on the floor.

13. Materials differ in their ability to reflect light from their surface. Mirrors are good reflectors of light and can form exact images. Do you notice something when you look at your imge in the mirror? Yes, your image is laterally inverted or reversed. Your left is the right of your image,and vice versa.

14. Refraction of light Have you ever tried looking at your feet from above the surface of water while you are in a swimming pool? What about trying to catch a fish in an aquarium? What have you observed in both situation? Perhaps, you have noticed that your feet look closer than they actually are and that catching the fish is more difficult than you thought it would be. Why do you think so?

15. Light bends as it move from one transparent material to another. This is called refraction. Experiments show that light travela slower in compact and thick materials than less compact materials. Thus light, travels slower in glass than in air. Refraction of light has some unusual effects in everyday life. One of this can be observed in swimming pools and other clear bodies of water. they appear to be shallower than they really are. The bottom seems to be nearer the surface. What precaution should you observe when you go swimming?

16. Why objects have color Imagine what our world would like if there is no color. Everything would just be black or white. It must be very boring. Colors make our world a happier place to live in. have you ever wondered how colors are formed? Why are some apples are red and other is green.

17. The sun emits white light. White light is actually made up of all the colors of the rainbow.; red, orane , yelow , green, blue, indigo and violet. By using a prism, you can break white light into these colors. A prism is a piece of glass or other see- through material that has several flat sides, called faces. When light passes through a prism, the light bens. As a result, the different colors that make up white light becomes separated.

18. An object appears to have color since it is able to select the colors it will absorb and reflect. For example, an apples to be red because it absorbs all colors except red. So if the red is reflected to our eyes, the apple appears to be red. An object will appear white if it does not absorb any colors, and black if it absorbs all colors.

19. SCIENE FACT It takes 1.255 seconds for light to get from Earth to the moon. There are parts of light that we cannot see but which animals can, like the ultraviolet (UV) rays that only insects can see.

20. Now you know! Light travels in straight lines and in all directions, but it cannot pass through all materials. Light can pass through transparent materials. Only some light can pass through translucent materials. Light cannot pass through opaque materials.

21. Refraction is the bending of light rays as they pass through different transparent materials. An object’s color depends on the colors it absorb and reflects.

22. Answer MORE TO DO P. 173