PhysicsChapter 6: Alternating Current
AC Through A Resistor
In a **purely resistive AC circuit**, current and voltage are in phase
Definition
In a purely resistive AC circuit, current and voltage are in phase.
Power
Suppose: v=V₀sinωt From Ohm's law: i=vR Therefore: i=(V₀R)sinωt or: i=I₀sinωt where: I₀=V₀R Thus current and voltage reach: zero together; positive maximum together; negative maximum together. Therefore phase difference: φ=0 Using RMS values: Vrms=IrmsR Since V and I are in phase: *Pavg=VrmsIrms and: Pavg=Irms²R**
Formula / Key Relation
**Vrms=IrmsR φ=0**
Exam preparation
Exam Focus
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Review the key facts, formulas and checks before you move on.AC Through A Resistor
Sticky Notes · Quick Revision
Pure R:
- V & I in phase
- `φ=0`
- `V=IR`
- Power factor = 1
60-second revision
- A pure resistor creates no phase difference.
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