Deviation is defined as the instantaneous difference between the actual value and which other value?

The correct answer is that deviation is defined as the instantaneous difference between the actual value and the set point. In control systems, the set point represents the desired or target level that a system aims to maintain. It serves as a benchmark against which the actual measurements are compared. When the actual value deviates from the set point, this indicates a need for adjustment to bring the system back to its desired state.

Understanding this relationship is crucial in fields such as engineering and process control, where maintaining specific parameters is essential for efficiency and safety. The set point provides a clear goal for the system's operation, allowing for effective monitoring and correction when deviations occur.