Suppose that you and a friend decide to use two different methods to make popcorn for a snack. Your friend uses a hot-air popcorn popper. You put a bag of microwave popcorn into a microwave oven.
Use what you know—about radiation, conduction, and convection—to explain how heat was transferred when your friend popped her popcorn and how heat was transferred when you popped your popcorn.
When your friend used a hot-air popcorn popper, the heat was primarily transferred through convection. The hot-air popcorn popper blows hot air onto the popcorn kernels, which then warms them up. Convection is the process where heat is transferred through the movement of a fluid (in this case, hot air). As the hot air blows over the kernels, it transfers its heat energy to them, causing them to pop and turn into popcorn.
On the other hand, when you put a bag of microwave popcorn into a microwave oven, the heat is transferred through radiation. Microwaves are a form of electromagnetic radiation that excites the water molecules within the popcorn kernels. This excitation causes the water molecules to vibrate, generating heat throughout the kernels. As a result, the heat generated inside the kernels leads to the popping of the popcorn.
It's important to note that in microwave ovens, some convection may also occur, but it plays a minor role compared to radiation. The heat generated by the microwaves tends to create convection currents within the microwave cavity, which helps distribute the heat evenly. This convection process assists in heating the kernels uniformly, ensuring that the popcorn pops uniformly as well.
In summary, your friend's hot-air popcorn popper primarily used convection to transfer heat, while your microwave oven used radiation as the main heat transfer mechanism.
so, what do you know?
what are the heat sources?