Final answer:
In a series RC circuit, when the resistance and capacitive reactance are equal, the phase angle between the voltage and current is 45 degrees.
Step-by-step explanation:
If the resistance and capacitive reactance are equal in a series RC circuit, the phase angle between the voltage and current will be 45 degrees. When resistance and capacitive reactance are equal, we can calculate the phase angle φ using the equation tan φ = XC/R, where XC is the capacitive reactance and R is the resistance.
Since XC/R equals 1 when they are equal, tan φ is 1, which corresponds to a phase angle of 45 degrees.
This result is halfway between the 0° phase difference found in a purely resistive circuit, where the voltage and current are in phase, and the 90° phase difference seen in a purely capacitive circuit, where the voltage and current are 90 degrees out of phase.