Question

Give reason as to why woolen clothes are more preferable in winter.

Answer 1

Hint: In this question, we will use some basic points of thermal conduction. To solve this question, we have to remember that both air and wool are bad conductors of heat.
Formula used: $Q={\displaystyle \frac{KA(T_1-T_2)t}{x}}$.

Complete step-by-step solution -
As we know that the woolen fibres encloses a large amount of air in them. Hence, the woolen clothes contain a large amount of trapped air in them.
We also know that both air and wool are bad conductors of heat.
The thermal conductivity is given by the relation:
$\Rightarrow Q={\displaystyle \frac{KA(T_1-T_2)t}{x}}$, here the proportionality constant K is called coefficient of thermal conductivity of the given material. Its value depends on the nature of the material.
The thermal conductivity of wool = 0.04 and air = 0.024.
The small coefficient of thermal coefficient prevents the loss of heat from our body due to conduction. Air does not allow the body heat to flow out, as the result of which we feel warm in woolen clothes.

Note: Whenever we ask such types of questions we should remember some basic points of thermal conductivity. We will relate the quantities with the formula of thermal conductivity and then by getting the small coefficient of thermal conductivity. We will get our answer.