Take-out coffee cups and containers are also made from styrofoam, to prevent the heat from escaping in the environment and to keep the drinks or the food hot. Some examples of insulation include having a layer of air trapped between the external and the internal walls, or some styrofoam. It keeps the food hot (or cold) because the space between its walls is filled with materials that have low thermal conductivity. An insulated portable flask or cup is very useful in this situation. For example, when going on a trip or taking lunch to work or to school, one may want to keep their soup or coffee hot. Materials with low thermal conductivity are used to keep the food’s temperature constant for a long time. To prevent burns people hold the highly conductive metal pots and lids by handles that are made from plastics and other materials with low thermal conductivity. Heaters of an electric stove, for example, are made from highly conductive metals, to ensure that they transfer heat to the pot well. The stove is also a good example of the use of thermal conductivity. Some chefs prefer to cook the custard on a double boiler to ensure low thermal conductivity. This works well with foods that burn easily or should not be boiled, like chocolate. The maximum temperature of the inner container will not exceed 100° C (212° F), the boiling point of water. For example, cooking on a double boiler reduces the overall conductivity because a metal pot that has direct contact with the heat has less conductive water inside, and then another pot with food is in the water. When one needs to control the overall conductivity, it can be decreased by choosing a pot made from different materials, or by adjusting the cooking method. When a metal pot is put on the heat source, it cooks the food by transferring this heat to the food. Because metals conduct heat well but can withstand high temperatures, they are used to make pots and pans. Thermal conductivity is very important in cooking. High heat conductivity is important when frying or grilling hamburger patties, and they are sometimes grilled directly on the metal grill with just a little oil to prevent them from sticking to the grill. It is used for regulating body temperature, for cooking, and for making people’s life comfortable, among other things. Thermal conductivity has many applications in technology and in everyday life. If she decides to lick a metal door handle, the heat from her tongue would quickly transfer to the metal, and the liquid on her tongue would likely get frozen and her entire tongue - stuck to the handle. For example, wool has much lower thermal conductivity than does metal, so if a child licks her mitten while outside in sub-zero temperature, nothing will happen to her. The higher the thermal conductivity of a material - the greater the heat transfer. It does, however, depend on the temperature. This property is independent of the size of the object. Thermal conductivity is a property of an object to allow heat to move through it. Thermal Conductivity of Common Materials Overview Animal and Human Internal Temperature Regulation
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