Answer :
Final answer:
The correct answer is b) Conduction heat transfer occurs chiefly through convection, characterized by the cyclical movement of fluid based on changes in density and temperature.
Explanation:
In convection between a lower hot layer and an upper cold layer, with downward being the direction of gravity, the heat transfer occurs primarily through convection. Convection refers to the transfer of heat by the mass movement of a fluid, which can be either a liquid or a gas. This process involves the warm air or fluid becoming less dense and rising, whereas the cooler air or fluid, being denser, sinks. This movement creates a convection current, which is a key method for heat distribution in fluids. In the given scenario, as the lower layer heats up, the fluid expands and rises towards the cooler layer above, while the cooler fluid descends, creating a cycle that effectively transfers heat from the lower to the upper layer.
Convection is the transfer of heat by the mass movement of a fluid, like air or water. In the scenario described, where a lower hot layer interacts with an upper cold layer through convection, the heat primarily transfers through convection. As the warm air rises and the cool air sinks, a convection current is created, illustrating this process. This is a fundamental concept of heat transfer mechanisms.
