PhysicsChapter 6: Alternating Current
AC Through An Inductor and Capacitor
An ideal **inductor** and capacitor
Definition
An ideal inductor and capacitor oppose alternating current through frequency-dependent reactance and create phase differences between voltage and current.
Pure Inductor
Inductive reactance: **XL=ωL=2πfL RMS current: I=VXL In a pure inductor: current lags voltage by 90°**. Increasing frequency increases `X_L`.
Pure Capacitor
Capacitive reactance: **XC=1ωC=12πfC RMS current: I=VXC In a pure capacitor: current leads voltage by 90°**. Increasing frequency decreases `X_C`.
Memory Rule
**L → current Lags C → current Comes first**
Formula / Key Relation
**XL=ωL XC=1ωC Inductor: I lags V by 90° Capacitor: I leads V by 90°**
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.AC Through An Inductor and Capacitor
Sticky Notes · Quick Revision
Inductor:
- `XL=2πfL`
- I lags V
- Capacitor:
- `XC=12πfC`
- I leads V
60-second revision
- Inductive reactance rises with frequency; capacitive reactance falls with frequency.
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