Capacitive reactance is considered negative because it represents the phase relationship between voltage and current in a capacitive circuit. In a capacitor, the current leads the voltage by 90 degrees, meaning that the voltage lags the current. This phase difference is mathematically expressed as a negative sign in the capacitive reactance formula, (X_C = -\frac{1}{\omega C}), indicating that the reactance opposes changes in voltage rather than current.
Inductive reactance.
A circuit that has only a capacitor in it. Or the net reactance is below zero, making it capacitive. The current leads the voltage in a negative (capacitive) reactive circuit.
Reactance is -1/2 pi F C so a 25 uF capacitor at 400 Hz would have a reactance of about -15.9 ohms. The negative sign indicates that capacitive reactance is leading, with current leading voltage.AnswerI would take issue with the previous answer that capacitive reactance is expressed as a negative value, or that it is 'leading'. Reactance is not a vector quantity, so it neither leads nor lags anything. In a (theoretically) purely capacitive circuit, it is the load current that leads the supply voltage. However, when using complex notation, capacitive reactance is expressed as -j 15.9 ohms, where 'j' is called an 'operator' -but even this does not mean that the reactance is 'leading', as it defines reactance in terms of a current phasor -in other words, the '-j' refers to the relative position of current to voltage, not reactance to impedance.
It isn't necessarily so. The capacitive voltage is the product of the current and capacitive reactance, while the inductive voltage is the product of the current and the inductive reactance. So it depends whether the capacitive reactance is greater or smaller than the inductive reactance!
Susceptance is the reciprocal of reactance, and is expressed in siemens (symbol: S). So, inductive susceptanceis the reciprocal of inductive reactance, and capacitive susceptance is the reciprocal of capacitive reactance.
Inductive reactance is traditionally positive while capacitive reactance is traditionally negative. Those are the conventions used by electrical engineers and they are consistent with a time-dependency of exp(+jwt).
Inductive reactance is traditionally positive while capacitive reactance is traditionally negative. Those are the conventions used by electrical engineers and they are consistent with a time-dependency of exp(+jwt).
The capacitive reactance of a capacitor increases as the frequency decreases.
Inductive reactance.
A circuit that has only a capacitor in it. Or the net reactance is below zero, making it capacitive. The current leads the voltage in a negative (capacitive) reactive circuit.
Because it is. Capacitive reactance is a form of resistance, along with inductive reactance. All are measured in ohms.
Since capacitive reactance is inversely-proportional to the supply frequency, as the frequency is increased, the reactance will decrease.
A circuit that has only a capacitor in it. Or the net reactance is below zero, making it capacitive. The current leads the voltage in a negative (capacitive) reactive circuit.
Inductive reactance, as well as capacitive reactance, is measured in ohms.
Reactance is -1/2 pi F C so a 25 uF capacitor at 400 Hz would have a reactance of about -15.9 ohms. The negative sign indicates that capacitive reactance is leading, with current leading voltage.AnswerI would take issue with the previous answer that capacitive reactance is expressed as a negative value, or that it is 'leading'. Reactance is not a vector quantity, so it neither leads nor lags anything. In a (theoretically) purely capacitive circuit, it is the load current that leads the supply voltage. However, when using complex notation, capacitive reactance is expressed as -j 15.9 ohms, where 'j' is called an 'operator' -but even this does not mean that the reactance is 'leading', as it defines reactance in terms of a current phasor -in other words, the '-j' refers to the relative position of current to voltage, not reactance to impedance.
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It isn't necessarily so. The capacitive voltage is the product of the current and capacitive reactance, while the inductive voltage is the product of the current and the inductive reactance. So it depends whether the capacitive reactance is greater or smaller than the inductive reactance!