Question

How do convection currents form?

A) When heated air expands, it becomes less dense, rises, and displaces cooler, more dense air, which moves downward.
B) When heated air expands, it becomes more dense, falls downward, and displaces cooler, less dense air, which rises.
C) When cooled air contracts, it becomes less dense, falls downward, and displaces warmer, more dense air, which rises.
D) When cooled air contracts, it becomes more dense, rises, and displaces warmer, less dense air, which falls downward.

Answer 1

Convection currents form when heated fluid or gas expands, becomes less dense, and rises, replacing the cooler, denser air, which then moves downward. This process is driven by buoyancy forces and can be observed in everyday examples like heating soup or using an oven.

Step-by-step explanation:

Convection currents form when there is a transfer of heat by the motion of matter, driven by buoyancy forces. As a fluid or gas is heated, it expands and becomes less dense, which creates buoyancy. This causes it to rise, and the cooler, denser material sinks due to gravity. For example, in an oven, the fire heats the air at the bottom, causing it to expand and become less dense, thus rising to the top and heating the food by convection. The correct choice describing how convection currents form is A) When heated air expands, it becomes less dense, rises, and displaces cooler, more dense air, which moves downward.