1 00:00:00,880 --> 00:00:10,839 Hello everyone, this is Kori, and today we are going to continue talking about heat and light. 2 00:00:11,380 --> 00:00:14,439 We will be focusing on light. 3 00:00:18,019 --> 00:00:28,460 Light is a form of energy emitted by luminous objects. 4 00:00:30,600 --> 00:00:35,780 Luminous objects are things like the sun or a light bulb. 5 00:00:35,780 --> 00:00:41,960 These objects emit or give off light energy. 6 00:00:45,810 --> 00:00:48,350 Light makes plants grow. 7 00:00:48,350 --> 00:00:57,700 At the beginning of the year, when you learned about cells, you learned that plant cells need light. 8 00:01:00,119 --> 00:01:03,060 Light allows them to grow. 9 00:01:07,659 --> 00:01:14,159 Light can be converted into electrical energy. 10 00:01:16,760 --> 00:01:27,239 Remember, energy can change form, so light energy can change to electrical energy. 11 00:01:30,810 --> 00:01:45,480 We can sense light using our sense of sight. We use our sense of sight when we use our eyes 12 00:01:45,480 --> 00:02:05,079 to see. Light enables us to see objects and distinguish shapes, sizes, and colors. If 13 00:02:05,079 --> 00:02:14,879 you are in a dark room and there is no light, you can't see objects. You don't know the 14 00:02:14,879 --> 00:02:25,060 shape, size, or color of the objects in the room. If you turn on the light in a room, 15 00:02:25,860 --> 00:02:36,240 you can see the objects. When there is light in a room, you can see the shape of objects. 16 00:02:36,240 --> 00:02:49,969 Is it a square, circle, rectangle? You can see the size. Is it big or small? The table 17 00:02:49,969 --> 00:03:01,129 is bigger than the chair. The lamp is smaller than the sofa. When there's light, you can 18 00:03:01,129 --> 00:03:16,800 also see the color. Is it red, green, or blue? Light travels in straight lines from its source. 19 00:03:19,560 --> 00:03:31,159 You can see this in our picture on the bottom right of the slide. Our source of light is the sun. 20 00:03:31,159 --> 00:03:45,039 Light from the sun travels through the window to the person's eye. The light moves in a direct 21 00:03:45,039 --> 00:03:59,039 way. It goes in a straight line. Now let's look at our concept map that shows sources of light. 22 00:03:59,039 --> 00:04:16,680 Light sources can be natural or artificial. Natural sources come from nature. The Sun is 23 00:04:16,680 --> 00:04:29,040 a natural source of light. Some living things are also natural sources of light. There are 24 00:04:29,040 --> 00:04:43,279 some types of bacteria, bugs, and fish that emit light. Artificial sources of light do not come 25 00:04:43,279 --> 00:04:53,439 directly from nature. They are man-made. Artificial sources of light require electricity. 26 00:04:53,439 --> 00:04:58,439 Light bulbs are an artificial source of light. 27 00:04:58,439 --> 00:05:14,529 Materials can be transparent, translucent, or opaque. 28 00:05:14,529 --> 00:05:21,529 Transparent materials allow light to pass through. 29 00:05:21,529 --> 00:05:25,529 Objects can be seen clearly. 30 00:05:25,529 --> 00:05:39,290 In this image, you can easily see through the transparent material. 31 00:05:39,290 --> 00:05:51,110 Translucent materials allow light to pass through, but objects cannot be seen clearly. 32 00:05:51,110 --> 00:06:01,670 In this image, you can see through the material because light is passing through, but you 33 00:06:01,670 --> 00:06:04,870 cannot see clearly. 34 00:06:04,870 --> 00:06:10,339 The object looks blurry. 35 00:06:10,339 --> 00:06:17,800 Opaque materials do not let any light pass through them. 36 00:06:17,800 --> 00:06:24,709 You can't see objects that are behind an opaque material. 37 00:06:24,709 --> 00:06:35,300 In this image, you can't see behind the opaque material. 38 00:06:35,300 --> 00:06:41,480 Let's review those types of materials again. 39 00:06:41,480 --> 00:06:48,339 Transparent materials allow all light to pass through. 40 00:06:48,339 --> 00:06:54,379 You can easily and clearly see through it. 41 00:06:54,379 --> 00:07:02,540 Glasses and windows are transparent materials. 42 00:07:02,540 --> 00:07:11,750 Can you think of more examples of transparent materials? 43 00:07:11,750 --> 00:07:20,029 Translucent materials allow some light to pass through. 44 00:07:20,029 --> 00:07:23,149 You can see light through the object, 45 00:07:23,149 --> 00:07:27,050 but the object is not clear. 46 00:07:28,050 --> 00:07:30,910 Stained glass and sunglasses 47 00:07:30,910 --> 00:07:34,029 are examples of translucent materials. 48 00:07:35,610 --> 00:07:43,709 Can you think of more examples of translucent materials? 49 00:07:43,709 --> 00:07:48,709 Opaque materials do not allow light to pass through. 50 00:07:48,709 --> 00:07:55,189 through. You can't see an object that is behind an opaque material. 51 00:07:57,269 --> 00:08:07,029 Wood is an opaque material. If you are standing behind a wooden door, you cannot be seen. 52 00:08:08,790 --> 00:08:19,639 Can you think of more examples of opaque materials? All right, that's all for now. 53 00:08:19,639 --> 00:08:21,379 Thanks for listening.