Use the terms radiation, conduction, and convection to explain how a pot of water boils.
When a pot of water is placed on a stove, the three modes of heat transfer - radiation, conduction, and convection - work together to bring the water to a boiling point.
Radiation: The heat source (usually a flame or an electric burner) emits thermal radiation. This radiation travels in the form of electromagnetic waves and transfers energy to the pot and the water molecules. The pot absorbs a portion of this radiation, converting it into heat energy.
Conduction: As the pot absorbs heat through radiation, the high-energy molecules in the pot start colliding with the adjacent molecules. This process is known as conduction. The molecules in the pot transfer their kinetic energy to the molecules in direct contact with them. Consequently, the heat energy is conducted from the bottom of the pot to the water molecules in direct contact with the pot's surface. As a result, the water molecules near the bottom of the pot gain energy and become hotter.
Convection: The heated water molecules at the bottom, which have absorbed the heat energy through conduction, become less dense and rise due to convection. This process is called natural convection. As they rise, cooler water from above flows down to replace them, creating a continuous flow of water. This movement of water molecules, driven by density differences caused by temperature variations, distributes the heat energy throughout the pot.
Together, radiation, conduction, and convection work in a continuous cycle. The heat radiation from the heat source is absorbed by the pot, which conducts the heat to the water molecules in direct contact. The heated water then rises due to natural convection, allowing cooler water to take its place. This cycle continues until the water reaches its boiling point, at which point the heat energy is sufficient to convert liquid water into water vapor, causing the pot of water to boil.