Question

In an AC circuit, what is the power factor of a pure resistor?

• A. \(0\)
• B. \(0.5\)
• C. \(1\)
• D. \(-1\)

Hint:

Power factor values:
• Pure resistor: \(1\)
• Pure inductor: \(0\) (lagging)
• Pure capacitor: \(0\) (leading) Maximum power transfer occurs when power factor is unity.

Answer 1

The Correct Option is C

Concept: The power factor in an AC circuit is defined as: \[ \text{Power Factor} = \cos\phi \] where \(\phi\) is the phase difference between voltage and current.

Step 1: Understand behavior of a pure resistor. In a purely resistive circuit:
• Voltage and current are in phase
• Phase difference \(\phi = 0^\circ\)

Step 2: Calculate power factor. \[ \cos 0^\circ = 1 \]

Step 3: Interpretation. A power factor of 1 means:
• All supplied power is effectively used
• No reactive power is present \[ \boxed{1} \]