Toasters do not have a specific mechanism to detect whether they are plugged in or not. The toaster's internal circuitry does not actively check if it is connected to a power source. Instead, a toaster simply functions as an electrical device that draws power from an outlet when it is plugged in.
When a toaster is plugged into a working electrical outlet, it completes the electrical circuit, allowing current to flow from the outlet through the toaster's heating elements and other components. This current generates heat in the heating elements, which then toasts the bread.
Conversely, when a toaster is not plugged in, there is no electrical connection between the toaster and the power source. As a result, no current flows through the toaster, and the heating elements remain inactive.
In summary, a toaster doesn't have a specific "awareness" of being plugged in or not. Its functionality simply depends on whether it is connected to a power source through a working electrical outlet.