The photo on the right shows a refrigerator. Explain why the freezer compartment is often located at the top of a refrigerator.
The air that is cooled in the freezer becomes denser and sinks. Warmer air flows in to be cooled. This creates a convection current which allows the entire refrigerator to be cooled more effectively.
*Note that this is an old design of a refrigerator. It is still commonly used in low-end refrigerators. The shelves are usually made of wires and allow air to circulate freely in the fridge. Most modern refrigerator have separate compartments and separate cooling systems for each compartments.