What is the function of the pressure diaphragm in the airspeed indicator?

The pressure diaphragm in the airspeed indicator plays a crucial role in determining the airspeed of an aircraft. It operates based on the principles of differential pressure. As the aircraft moves through the air, it generates dynamic pressure, which is the result of the airflow entering the pitot tube. This dynamic pressure acts on one side of the diaphragm, while the atmospheric pressure, measured from the static port, acts on the other side.

As the dynamic pressure increases with the increase in speed, it causes the diaphragm to flex or expand. This flexing movement is what translates into a visual indication of the aircraft's airspeed on the indicator's dial. Therefore, the diaphragm is vital in converting air pressure differences into a readable value, allowing the pilot to understand the aircraft's speed relative to the surrounding air.

The other functions listed in the options do not relate to the operation of an airspeed indicator. For example, measuring temperature, monitoring fuel levels, and controlling exhaust pressure involve different systems and components entirely, such as temperature probes, fuel gauges, and exhaust probes, respectively. The specific design and purpose of the pressure diaphragm are integral to providing accurate speed readings, making it a key component of the airspeed indication mechanism.