In transfer of heat topic, the heat transfers from one object to another until the heat becomes equal. But why does the heat not transfer from a hot box to another object??
In transfer of heat topic, the heat transfers from one object to another until the heat becomes equal. But why does the heat not transfer from a hot box to another object??
A vacuum flask is nothing but a bottle inside a bottle separated by a vacuum. This is because with a vacuum surrounding the bottle, conduction is effectively minimized. There is nothing in contact with the bottle except the part that holds the inside bottle in place. But there is still a small bit of contact, which makes the inside bottle conduct heat to a small degree. If, however, you want to accelerate the process of cooling your drink down using a freezer (by speeding up the transfer of heat, instead of minimizing it), you have to surround your drink with something that conducts heat very well, like a wet paper towel, because water conducts heat much better than the air inside of a refrigerator.
By doing this, heat transfer is not entirely eliminated because of radiation. Every object radiates heat to some degree (depending on how hot the object is). A hot liquid in the inside bottle will still radiate heat, or the outside bottle will still radiate heat toward the liquid inside the bottle. To minimize this, the surface is coated with silver. Silver prevents electromagnetic waves from passing, thus it keeps the radiation at bay
A vacuum flask is nothing but a bottle inside a bottle separated by a vacuum. This is because with a vacuum surrounding the bottle, conduction is effectively minimized. There is nothing in contact with the bottle except the part that holds the inside bottle in place. But there is still a small bit of contact, which makes the inside bottle conduct heat to a small degree. If, however, you want to accelerate the process of cooling your drink down using a freezer (by speeding up the transfer of heat, instead of minimizing it), you have to surround your drink with something that conducts heat very well, like a wet paper towel, because water conducts heat much better than the air inside of a refrigerator.
By doing this, heat transfer is not entirely eliminated because of radiation. Every object radiates heat to some degree (depending on how hot the object is). A hot liquid in the inside bottle will still radiate heat, or the outside bottle will still radiate heat toward the liquid inside the bottle. To minimize this, the surface is coated with silver. Silver prevents electromagnetic waves from passing, thus it keeps the radiation at bay
