1 00:00:00,000 --> 00:00:10,259 Hello everyone, this is Cori. I hope you are doing well. Today I am going to be talking 2 00:00:10,259 --> 00:00:27,339 with you about heat and light. Heat is a form of energy that passes from a hotter object 3 00:00:27,339 --> 00:00:39,859 to a colder one. For example, the sun is a hotter object than the earth. The sun 4 00:00:39,859 --> 00:00:54,640 passes energy to the earth. An object gets warmer when it absorbs heat and gets cooler 5 00:00:54,640 --> 00:01:10,540 when it gives off heat. So when we heat something up on the stove, let's say we heat a pan on the 6 00:01:10,540 --> 00:01:23,400 stove, the pan gets warmer. The pan will take in heat. It will absorb heat from the stove 7 00:01:23,400 --> 00:01:32,500 and the stove will get somewhat cooler as it gives off heat to the pan. 8 00:01:33,400 --> 00:01:39,060 So an object gets warmer as it takes in heat 9 00:01:39,060 --> 00:01:48,560 and the object that is giving off heat gets cooler as it loses heat and sends it off. 10 00:01:48,560 --> 00:01:57,379 A source of heat is anything that produces heat. 11 00:02:00,159 --> 00:02:03,319 There are natural sources of heat. 12 00:02:04,120 --> 00:02:09,740 These are sources that are caused by nature. 13 00:02:12,000 --> 00:02:17,939 For example, the sun or lava from a volcano. 14 00:02:19,120 --> 00:02:23,099 We also have artificial sources of heat. 15 00:02:23,639 --> 00:02:25,979 These are things that are made by humans. 16 00:02:27,439 --> 00:02:31,800 For example, heaters or radiators are artificial sources of heat. 17 00:02:32,479 --> 00:02:37,280 Many of us have a heater or radiator in our home to keep us warm. 18 00:02:38,000 --> 00:02:41,719 At school, we have heaters as well in every classroom. 19 00:02:42,020 --> 00:02:47,500 Light bulbs are also artificial sources of heat. 20 00:02:48,180 --> 00:02:52,240 And wood fires are artificial sources of heat. 21 00:02:52,240 --> 00:03:05,719 Temperature is the measure of how hot or cold something is. 22 00:03:06,960 --> 00:03:14,280 We measure this, we measure temperature, using a thermometer. 23 00:03:15,900 --> 00:03:17,939 Thermometers can be analog. 24 00:03:19,560 --> 00:03:24,599 With analog thermometers, we read the temperature on a scale. 25 00:03:24,599 --> 00:03:34,379 Thermometers can also be digital. With digital thermometers we read the temperature on a screen. 26 00:03:34,379 --> 00:03:47,150 Here you can see an analog and a digital thermometer. Over here we've got the analog 27 00:03:47,150 --> 00:03:56,389 thermometers. To figure out how hot or cold it is we have to look at our scale. We'll follow 28 00:03:56,389 --> 00:04:06,409 this red line all the way up and we can see that the temperature is 21 degrees 29 00:04:06,409 --> 00:04:15,169 Celsius. Now over here we have our digital thermometers. To figure out the 30 00:04:15,169 --> 00:04:22,970 temperature on a digital thermometer we just have to look at the screen. On this 31 00:04:22,970 --> 00:04:37,740 screen we see that the temperature is 31.2 degrees Celsius. Heat can be 32 00:04:37,740 --> 00:04:49,209 transferred by conduction, convection, or radiation. Conduction is when two 33 00:04:49,209 --> 00:04:57,490 objects are in contact, they are touching, and when these objects are in contact 34 00:04:57,490 --> 00:05:06,730 heat is transferred from one object to the other. The temperature of the colder 35 00:05:06,730 --> 00:05:16,350 object increases, the temperature of the colder object goes up, gets warmer, and 36 00:05:16,350 --> 00:05:24,149 the hotter object gets colder. That means the temperature of the hotter object 37 00:05:24,149 --> 00:05:38,100 goes down. We can see conduction when we touch a hot stove. The temperature of 38 00:05:38,100 --> 00:05:45,300 your hand will increase. Your hand is colder than the stove. When you touch a 39 00:05:45,300 --> 00:05:51,300 hot stove, your hand becomes hot and you'll probably get a burn. That is an 40 00:05:51,300 --> 00:05:58,500 example of conduction. Energy is transferred by direct contact. Next we 41 00:05:58,500 --> 00:06:08,160 have convection. With convection thermal energy travels through a gas or through 42 00:06:08,160 --> 00:06:17,759 a liquid. There is a circular movement as the hotter molecules rise up and colder 43 00:06:17,759 --> 00:06:28,800 molecules move down. You can see this circular movement in our picture. As we heat water up, 44 00:06:29,360 --> 00:06:34,959 the thermal energy travels through the liquid in a circular movement. 45 00:06:36,800 --> 00:06:47,819 Next we have radiation. Thermal energy can be transferred through space by electromagnetic 46 00:06:47,819 --> 00:06:56,620 waves. An example of this is when thermal energy from the sun is transferred to the earth. 47 00:06:58,459 --> 00:07:05,660 Here we can see the sun is keeping these people warm at the beach. It makes the sand warm and the 48 00:07:05,660 --> 00:07:13,339 water warm because the thermal energy moves through a lot of space to get to the earth. 49 00:07:13,339 --> 00:07:21,670 Alright, now I hope you continue to work hard and take care of yourselves. 50 00:07:21,670 --> 00:07:22,490 Goodbye for now!