Question

When a kettle is placed on the stove and water begins to boil, the hotter water at the bottom begins to rise and the cooler water above it begins to sink. What type of heat transfer does this situation represent?

Answer 1

This is processs of convection

Answer 2

This motion is caused by convection. It is the movement only by fluid. It happens because hotter fluid expands, making it less dense, therfore it rises. Meanwhile cooler fluid contracts, making it denser, resulting in sinking. That's why a convection current is created.