In a series AC circuit with only capacitive reactance and resistance, how does the current behave in relation to the voltage?

In a series AC circuit that contains only capacitive reactance and resistance, the behavior of current in relation to the voltage is such that the current leads the voltage by 90 degrees. This phenomenon occurs because, in capacitive circuits, the nature of how capacitors store and release energy results in a phase shift.

When an AC voltage is applied to a capacitor, the current reaches its peak value before the voltage does. This is due to the capacitor charging and discharging in response to the changing voltage. As a result, the current waveform "leads" the voltage waveform by a quarter of a cycle, effectively measured as 90 degrees.

This unique property of capacitive circuits can be critical in understanding how these components interact in various AC applications, especially in tuning circuits or in power factor correction. In summary, the leading behavior of the current signifies a key characteristic of capacitive elements in AC circuits, making it essential to grasp this concept for effective circuit analysis and design.