Power Measurement

True power (real power):

P = V_rms × I_rms × cos(φ)

Where φ = phase angle between V and I.

For resistive load (speakers): cos(φ) ≈ 1 at midrange frequencies. Becomes complex at resonance.

Apparent power (VA):

S = V_rms × I_rms

Reactive power:

Q = S × sin(φ)

For practical amplifier measurement:

Use true RMS voltmeter and current clamp. Measure DC current and voltage:

P_supply = V_supply × I_supply
P_output = V_speaker_rms² / R_speaker
η = P_output / P_supply

[VISUAL PLACEHOLDER: PowerMeasurementSetup.png] Description: Diagram showing current clamp on positive power wire, voltmeter across amplifier power terminals, and RMS voltmeter across speaker load, with formula overlay

END OF CHAPTER 6

Chapter 6 Statistics: - Word count: ~5,500 words - Page equivalent: ~11 pages - Sections: 6 of 6 complete ✅ - Three-tier structure: Reference format (single tier — this chapter is a math library, not tiered instruction) - Visual placeholders: 9 identified