1. Welcome to Our Group Presentaions Class : 12 science 2 Pratiwi nengsi (22) Nurdiana ahmad (20) Nurlindah kamaruddin (21)

2. explanation text is a text genre which tries to explain how a thing happens or why the thing is made. Explanation text actually is similar to procedure text, however, explanation text tends to explain. While theprocedure text is intended to instruct how to form or make something. What is explanation text? Purpose An explanation is used to tell how or why something happens. These are the structure of explanation text: A general statement which describes or identifies the phenomenon A series of statements that tell how or why the feature or process changes. Words should show cause and effect. A conclusion/application sums up the explanation and talks about its applications; may also give examples 3. How Rainbow form ? Rainbow is one of the beautiful scenery that we rarely see. If seen, the shape of a rainbow as an arc in the sky appears blue due to refraction of the sun when it rains roughly where ya rainbow can be seen? Usually the rainbow can be seen in mountainous areas or when overcast or when the rain had stopped falling. 4. Rainbow is the only electromagnetic waves we can see. It consists of some of the color spectrum. Friends can mention what are the colors that we can see in the rainbow? Among the colors are: red, yellow, green, blue, orange, purple. And in fact there are other colors that we can not see with your eyes directly. The color red has the greatest wavelength, while violet has the smallest wavelength. How is a rainbow formed? Let us observe when sunlight is about right-angled mirror or prism edge glass, soap scum or a surface, we see different colors in the light. 5. White light from the Sun has to hit the raindrops at a certain angle before a rainbow is possible. It is best if the sun is fairly low in the sky such as dawn and late afternoon. The angle is important as it effect the direct the light travels after it hits the raindrops and that determines whether or not we will see a rainbow. 6. It is possible to see through a glass window but, at the same time, see your own reflection. This is because the window both transmits and reflects light. Water can do this too - that is why you can see a reflection in a pool of clean water and also see the bottom. When light from the sun hits a water droplet, some of the light is reflected. This light will obey the Law of Reflection. 7. The light that is not refracted crosses the air-water interface (boundary layer). When this happens it slows down because the water is more dense than the air. The reduction of speed cause the path of the light to bend - this is called refraction. In this case the path of the light rays bends toward the normal line. 8. White light is made up of a spectrum of colours, each with its own wavelength. Different wavelengths travel at different speeds and when they encounter a change to medium that is more dense or less dense, the speeds are efected by different amounts. Hence, the colours separate. This phenomenon is know as Dispersion. 9. At the rear of the raindrop, the light hits the water-to-air interface. If the angle of incidence is greater than the critical angle, Total Internal Reflection will occur. A rainbow will only be seen if this happens, otherwise the light will continue out the other side of the raindrop and continue to move away from the would-be viewer. 10. Just as the light changed speed as it entered the raindrop, its speed changes again as it leaves. Here, the light is moving from a more dense medium (water) to a less dense medium (air). As it does so, it speeds up and its path bends. In this case the path of the light rays bends away from the normal line. This is another example of refraction. As the rays are refracted once again, the various wavelengths are effected to different extents. The overall result of this is increased separation of the component colours of white light. This is Dispersion. 11. Rainbow can only be seen when the rain along with the sun shining, but from the opposite side to the viewer. Our position should be between the sun and the water drops with the sun dibekalang us. The sun, the eye and the center of the arc rainbow shall be in a straight line. 12. So, if you already understand how and why the rainbow can be formed? I think the answer is yes, right ? 13. OK, thanks for you attention guys see you next time BYE !!!