What key indication suggests a change in voltage when current flows through all components and output resonates frequency?

The key indication that suggests a change in voltage when current flows through all components and the output resonates at a particular frequency is voltage itself. In an electrical circuit, particularly in resonant circuits, the relationship between voltage and current is critical.

When a circuit resonates, it means that the frequency of the current matches the natural frequency of the components, leading to a maximum voltage across certain components, such as capacitors or inductors. This phenomenon is due to the reactive components of the circuit (inductors and capacitors) storing and releasing energy, which results in significant variations in voltage even if the current may be steady.

In resonant circuits, small changes in current can lead to considerable changes in voltage across these components, and the voltage can oscillate in response to the resonant frequency. This relationship is fundamental in understanding how resonant circuits operate and how they affect the overall circuit behavior. Hence, observing changes in voltage is key to analyzing the circuit's performance and its response to different frequencies.