21.1.4—Root-mean-square (r.m.s.) and peak values and recall and use I r.m.s. = I0 /
- Syllabus
- 9702–2028–2029
- Objective
- 21.1.4
- Level
- A2
RMS values give the DC-equivalent heating effect: I_rms=I₀/√2 and V_rms=V₀/√2
For a sinusoidal AC signal, rms current or voltage produces the same mean power in a resistor as a DC value: I_rms=I₀/√2 and V_rms=V₀/√2.
Use rms values in P=VI or P=I²R for resistive loads, and specify whether a quoted AC value is rms or peak.
A 10 A peak sinusoidal current has I_rms≈7.07 A.
RMS is not the arithmetic average of a symmetric waveform, which is zero.
ConceptA-Level CAIE Physics A2