Woolen clothes keep us warm in winter. Which one of the following is reason for this? (A) Wool is a good conductor of heat. (B) Air is trapped in between wool fibres which keeps us warm. (C) Trapped air in woolen clothes prevents the heat transfer from our body to cold surrounding. (D) Trapped air in woolen clothes does not allow cold air to get inside us.
(B) and (C)
Wool is actually a poor conductor of heat, not a good one, so statement (A) does not correctly explain the warmth and is false.
Wool fibres are loosely arranged and trap air in between them, so statement (B) is true.
Since air is a poor conductor of heat, the air trapped within the woolen fibres prevents the heat of our body from escaping to the cold surroundings, keeping us warm, so statement (C) is true.
The trapped air works by stopping the outward flow of body heat rather than by physically blocking cold air from entering, so statement (D) does not correctly describe the reason and is false.
Hence, woolen clothes keep us warm because of statements (B) and (C).
Similar Questions
Which material would you choose to wrap a box of ice cream to prevent it from melting in summers?
Important Questions from Heat and Transfer
In summer season, the top and outer surface of the house are painted white because:
On a hot summer afternoon, the tent made up of fabric will be preferred as white colour is:
The coil of wire used in electric heaters is called a/an________.
Transfer of heat by convection can take place in
A body in motion essentially acquires
A. Kinetic energy
B. Potential energy
C. Mechanical energy
D. Heat energy
