Woolen cloths keep us warm in winter because:

Appeared in: ISRO 2024

Explanation

Wool is a poor conductor of heat, which means it acts as a thermal insulator.
The structure of woolen fibers is crimped, which allows it to trap a large volume of air.
This trapped air is the key to insulation, as air itself is a very poor conductor of heat.
By creating a barrier of trapped air, wool prevents the heat generated by the body from escaping into the colder environment, thus keeping the person warm.

Option A: Clothes are passive items and do not generate their own heat. The warmth comes from retaining the heat produced by the body's metabolic processes.
Option B: This is the opposite of how wool works. A good conductor would rapidly transfer heat away from the body, making a person feel colder in a cool environment.
Option D: While wool does act as a physical barrier to wind, which reduces heat loss from convection, its primary insulating mechanism is trapping a layer of still air to prevent conductive heat loss. This option is less precise and complete than the correct answer.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Heat Transfer and Insulation as background academic context rather than a clinical decision trigger.
The principle of insulation is fundamental to nursing care, particularly in thermoregulation. Nurses use blankets (wool or cotton) to keep patients warm and prevent hypothermia, especially in operating rooms, post-anesthesia care units, and for neonatal or elderly patients.
In emergency first aid for exposure or trauma, preventing heat loss is critical to patient survival. Covering the person with blankets or insulating materials helps maintain core body temperature and prevent shock.
What if? If a patient has a high fever (hyperthermia), the nurse's action would be the opposite. Instead of adding insulating layers, the nurse would remove blankets and excess clothing to promote heat loss to the environment, helping to lower the body temperature.

How to Approach the Question

Identify the core question: It asks for the scientific reason why wool provides warmth.
Recall the basic principles of heat transfer: heat flows from a warmer object to a cooler one. To stay warm, you must slow down this heat loss.
Analyze the options in the context of heat transfer.
Option A (produces heat): Discard this immediately. Passive clothing cannot generate heat.
Option B (good conductor): A good conductor would speed up heat loss, making you feel cold. This is the opposite of the desired effect. Discard this.
Option C (prevents heat escape): This describes insulation. Materials that trap air are good insulators because air does not conduct heat well. This is a plausible mechanism for staying warm.

Concept Tested & Keywords

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E6 Physiology Ganong 27e Vol 1 Part 2 p. 97-99

Practise the full ISRO 2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.