Question

Two thin blankets keep more hotness than one blanket of thickness equal to these two. The reason is
A. Their surface area increases
B. A layer of air is formed between these two blankets, which is a bad conductor
C. These have more wool
D. They absorb more heat from outside.

Answer 1

Hint: As we know that in winter times, the blanket, and sweaters are used to keep the body warmer even though the outer environment is cooler. The blanket is made of wool, and it is a bad conductor of heat, and the pores in the blanket are filled with air, which is also a bad conductor of heat.

Complete step by step solution:
In the single blanket case, we have only a thick blanket that is acting as a barrier for the heat from transmitting from the hot side to the cold side. Whereas on the double blanket side since we have thinner blankets, we also end up having a thin air packet gap between those two blankets, and as we know the air has a very low thermal conductivity value.

Since the thin packet of air has very low thermal conductivity it acts as an insulator preventing heat from transmitting across it. Hence the transmission of heat from the hot side to the cold side of one to the other blanket is very low when compared to the thick blanket.

Hence, option B is the correct answer.

Note: Just think about how the air transfers heat from one body to the other and this is because of the convection mode of heat transfer. From the different states, the heat is transferred by the movement of the molecules in the medium.