I found two different answers to this, the first one and the last answer. I don\
ID: 1469433 • Letter: I
Question
I found two different answers to this, the first one and the last answer. I don't know which is the correct one.
On a cool night you make your bed with a thin cotton sheet covered by a thick wool blanket. As you lay there all covered up, heat is leaving your body, flowing though the sheet and the blanket and into the air of the room. (The trick, of course, is to have enough blankets to make the flow of heat just right... If not enough flows you will be too hot and if too much flows you will be cold). Compare the amount of heat that flows though the sheet to the amount of heat that flows through the blanket.
Options are:
More heat flows through sheet than through the blanket.
More heat flows through blanket than through the sheet.
The same amount of heat flows through sheet and through the blanket
More heat flows through sheet than through the blanket.
More heat flows through blanket than through the sheet.
The same amount of heat flows through sheet and through the blanket
Explanation / Answer
Heat transfer is more through cotton than through wool because the thermal conductivity of cotton (0.23) is more than wool (0.4).
Heat transfers from Hotter body to a colder body.
As the given night is cold, our body loses heat into the surroundings, which makes us feel cold.
Therefore, to stop / reduce the heat flow or transfer we will wear woolen clothes.
The above cases are valid only when considered wearing / covering them individually.
When used together, heat transfer is based on the effective thermal resistances of the two covers.
This is similar to the case of electrical resistors in series. Even if we connect two different resistors in series, the current flow through them remains same.
Therefore, from the given options, "The same amount of heat flows through sheet and through the blanket ". is the correct one.
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