RC circuits — does the total current always lead the source voltage?

Introduction / Context:This item checks phase intuition: in networks containing only resistors and capacitors (no inductors), is the net current ahead (leading) or behind (lagging) the source voltage?

Given Data / Assumptions:

• RC network (series or parallel) with sinusoidal excitation.
• No inductive elements present.

Concept / Approach:Capacitive current leads voltage by 90 degrees for an ideal capacitor. The presence of resistance reduces the lead, but cannot reverse it to a lag because there is no inductive reactance to pull the phase negative. Therefore, the total current in an RC-only network leads the source voltage by some angle between 0 and +90 degrees.

Step-by-Step Solution:

Verification / Alternative check:Compute the input admittance Y = G + jB for an RC network; susceptance B = +ωC > 0, so the current phasor leads the voltage phasor by angle φ = arctan(B/G) ≥ 0.

Why Other Options Are Wrong:

• “False” would suggest zero or lagging phase for some RC arrangement, which would require inductive behavior not present in R–C-only circuits.

Common Pitfalls:Confusing “output current in a branch” with “total line current.” Individual branch currents may have different phases, but the total seen by the source still leads for RC-only networks.

Final Answer:True