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Why is capacitive reactance negative?

Updated: 12/21/2022
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Q: Why is capacitive reactance negative?
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What does capacitive reactance oppose?

Inductive reactance.


What is a capacitive reactive circuit?

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.


What is the reactance of a 25 uf capacitor when the applied frequency is 400 hz?

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.


Why is capacitive voltage higher than inductive voltage in an R-L-C circuit?

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!


What is meant by susceptance in electrical engineering?

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.

Related questions

What is the relationship of capacitive and inductive 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).


What is the phase relationship of capacitive and inductive 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).


The capacitive reactance of a capacitor increase as?

The capacitive reactance of a capacitor increases as the frequency decreases.


What does capacitive reactance oppose?

Inductive reactance.


What is a capacitive reactive circuit?

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.


What is the reason that capacitive reactance measured in ohms?

Because it is. Capacitive reactance is a form of resistance, along with inductive reactance. All are measured in ohms.


What is a reactive circuit?

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.


When the frequency of an applied voltage is increased the capacitive reactance of a circuit will?

Since capacitive reactance is inversely-proportional to the supply frequency, as the frequency is increased, the reactance will decrease.


What is the unit of inductive reactance?

Inductive reactance, as well as capacitive reactance, is measured in ohms.


What is the reactance of a 25 uf capacitor when the applied frequency is 400 hz?

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.


Why is capacitive voltage higher than inductive voltage in an R-L-C circuit?

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!


What are capacitive and inductive reactance?

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