Question

practice it!
select the statement that accurately describes convection.
in an air popper, thermal energy transfers from the heating element to air, then from that air to the popcorn kernels.
an air popper works by transferring thermal energy from the heating element to the popcorn kernels by direct contact.
popcorn is made in an air popper when air warms the heating element, then thermal energy is transferred to the popcorn kernels.
air poppers pull heat from the outside air, then transfer that thermal energy to the heating element, which heats the kernels by direct contact.

Explanation:

To determine the correct statement about convection, we analyze each option:

1. First option: In an air popper, the heating element heats the air (a fluid), and then the heated air (through convection, as warm air rises and carries heat) transfers thermal energy to the popcorn kernels. This matches the concept of convection (heat transfer via fluid movement).
2. Second option: "Direct contact" implies conduction, not convection. So this is incorrect.
3. Third option: Air does not warm the heating element (the heating element is the source of heat). So this is incorrect.
4. Fourth option: Air poppers don't pull heat from outside air to heat the element, and "direct contact" is conduction, not convection. So this is incorrect.

Answer:

In an air popper, thermal energy transfers from the heating element to air, then from that air to the popcorn kernels.