MCAT Flashcards: Convection

What is convection? Ken Tao is an MCAT expert and explains that it’s heat transfer by the motion of molecules in a fluid. Warmer parts of the fluid will expand and rise while cooler parts will sink. Occurs with liquids and gases but not solids.

Full Transcription

In this flash card video, we’re going to discuss “What is convection?”

Convection is heat transfer by the motion of molecules and fluid.

Remember, fluids include both liquids and gases. So as an example of how convection works, let’s say you have a candle with a flame. If you take your hand you put it a couple feet above the candle, you’re going to feel warmth. And since your hand is not in direct contact with the flame, this heat transfer is not due to conduction. It’s by convection. So how is this happening?

Well, the flame of the candle is going to heat up the air around it. The air around it is then going to get warm, and when air gets warm, it’s going to expand. And when it expands it becomes less dense so that warm air is going to travel upwards. So that’s how you’re able to feel the warmth above the flame. That is heat transfer body convection.