What is the effect of applying carburetor heat on the fuel-air ratio?

Applying carburetor heat affects the fuel-air mixture by causing the fuel to become richer. When carburetor heat is applied, the temperature of the air entering the carburetor increases. Warmer air has a lower density compared to cooler air, which means that the volume of air that enters the carburetor is reduced for a given throttle setting.

Because the same amount of fuel is mixed with less air, the overall mixture becomes richer, meaning there is a higher proportion of fuel to air. This is especially important in preventing and addressing issues such as carburetor icing, where ice formation can disrupt airflow and the mixing of fuel and air, leading to engine performance issues. Richening the mixture by applying carburetor heat helps counteract these situations and ensures smooth engine operation.

The other options involve changes in the mixture, however, they do not accurately describe the effect of applying carburetor heat. Understanding this concept is crucial for pilots to manage engine performance effectively, especially in varying atmospheric conditions.