Pure resistors — is the resistor’s voltage always out of phase with the current?

Introduction / Context:Phase relationships between voltage and current define how elements store or dissipate energy. This item checks the unique, purely dissipative behavior of an ideal resistor.

Given Data / Assumptions:

• Ideal resistor R only; no reactive components.
• Sinusoidal steady-state excitation.

Concept / Approach:In a pure resistor, voltage and current are in phase. Inductors and capacitors cause phase shifts of +90 degrees (current lags) and −90 degrees (current leads), respectively; resistors cause none.

Step-by-Step Solution:

Verification / Alternative check:Instantaneous power p(t) = v(t) * i(t) is always non-negative for a resistor, consistent with no reactive energy exchange and reinforcing zero phase shift.

Why Other Options Are Wrong:

• Selecting “True” confuses resistors with reactive elements that store energy and introduce phase shifts.

Common Pitfalls:Assuming some phase difference must exist because AC is involved. AC does not guarantee phase shifts; it depends on element type.

Final Answer:False