MCQ Detailed View

Heat transfer occurs in three main ways: conduction, convection, and radiation. In this scenario, water inside a kettle is heated mainly by convection. This means the heat from the flame warms the water molecules at the bottom of the kettle. These warmer molecules rise, while cooler molecules sink, creating a circular motion that distributes heat throughout the water.

Now, when a person is sitting near a fire, there is no physical contact with the flame, and the surrounding air is not moving strongly enough to carry all the heat directly. Instead, the person feels warm because of radiation. Radiation is the process in which heat energy travels in the form of electromagnetic waves, mainly infrared rays, without requiring a medium. These waves can travel through air or even a vacuum and directly heat objects in their path.

Conduction is not responsible here because the person is not touching the fire or any object in contact with it. Convection is limited to the movement of warm air around the fire but is not the primary way heat reaches the person. Reflection is unrelated to heat transfer; it refers to the bouncing back of light or sound waves.

Radiation is the main reason you can feel heat from the sun even though it is millions of kilometers away. Similarly, sitting near a fireplace or campfire feels warm because thermal radiation directly transfers energy from the flame to your skin and clothes.

This question belongs to Physics, specifically to the topic of heat transfer mechanisms, which explains how energy moves between objects in different conditions. Understanding conduction, convection, and radiation is essential to explain many real-life phenomena, including heating systems, cooking methods, and energy transfer in nature.