1. In the real world there are many insulators that you encounter every day. Give an example of a material that is an insulator and another material that is a conductor that you may use on a regular basis. Why do you think these materials were chosen for their particular function?
2. Food stores usually frozen foods that are open at the top. Why does the warm air not melt the food?
1. Styrofoam insulates, copper conducts.
2. Warm air rises.
Thanks
1. An example of an insulator is rubber. Rubber is commonly used in electrical wires and cables as an insulating material because it does not conduct electricity well. It has high resistance to the flow of electric current, making it an effective insulator. Another example is Styrofoam, which is commonly used to insulate food and beverages as it has low thermal conductivity, preventing heat transfer.
On the other hand, an example of a conductor that you may use on a regular basis is copper. Copper is an excellent conductor of electricity, which is why it is commonly used in electrical wiring and components. It allows the flow of electric current with low resistance, making it suitable for transmitting electricity efficiently. Aluminum is another commonly used conductor, especially in power transmission lines due to its high conductivity and relatively low cost.
The choice of materials for their particular function depends on their electrical or thermal properties. Insulators are chosen to prevent the flow of electricity or heat, while conductors are chosen to allow the flow of electricity or heat. Factors such as resistance, thermal conductivity, cost, and availability play a role in selecting the materials for their specific functions.
2. When frozen foods are stored open at the top in food stores, warm air does not melt the food due to a principle called convection. Convection is the process of heat transfer through the movement of fluid (in this case, air).
As warm air rises, it creates a convection current where the warmer air near the ceiling of the store is replaced by cooler air from the floor. The frozen foods are situated closer to the colder air near the floor, which helps maintain their frozen state. Since warm air tends to rise and cooler air stays closer to the ground, the warm air does not directly come into contact with the frozen foods, preventing them from melting.
In addition to convection, the open-top design of food displays in stores often incorporates insulated materials like glass or plastic barriers to further minimize heat transfer. These barriers act as insulators, creating a physical barrier between the warm external environment and the frozen foods.