Electricity & Magnetism
Capacitive Reactance
Opposition to AC current flow by a capacitor.
Variables
X_CΩ
Capacitive reactance
Opposition to AC by capacitor
ωrad/s
Angular frequency
ω = 2πf
CF
Capacitance
Capacitance
Derivation
From I = C(dV/dt) for V = V₀sin(ωt), X_C = V₀/I₀ = 1/(ωC).
Your notes
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Common questions
What is the Capacitive Reactance formula?
Capacitive Reactance is written X_C = 1/ωC. Opposition to AC current flow by a capacitor. It belongs to Electricity & Magnetism, under AC Circuits.
What are the units in X_C = 1/ωC?
In SI units, X_C is capacitive reactance, measured in kg·m²/(A²·s³); ω is angular frequency, measured in s⁻¹; C is capacitance, measured in A²·s⁴/(kg·m²).
How is the Capacitive Reactance formula derived?
From I = C(dV/dt) for V = V₀sin(ωt), X_C = V₀/I₀ = 1/(ωC). The result is X_C = 1/ωC.