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There has to be current before there is voltage. If a battery is connected via a resistor to a capacitor, the initial current is just V/R. Charge (current times time) flows into the capacitor and its voltage rises until it reaches the battery voltage, when the capacitor is fully charge and no more current flows.
In an AC circuit the current in the capacitor leads the voltage by one quarter of a cycle, or 90 degrees of phase.
Important equations for a capacitor:
Q=CV . . . charge = capacitance (in Farads) times voltage
I = C dV/dt . . . current = capacitance times rate of change of voltage.
In an AC circuit, replace d/dt by jw where w = 2.pi times frequency:
I = jwCV
What else can I help you with?
How many degrees are the current and voltage out of phase in a pure capacitive circuit?
In a pure (ideal) capacitive circuit, current leads voltage by 90 degrees.
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.
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 it mean to say that an alternating current leads or lags an alternating emf?
It is another way of saying that the circuit is capacitive reactive circuit. Look up the mnemonic ELI the ICE man. ELI, voltage leads the current in an inductive circuit. ICE, current leads the voltage in a capacitive circuit.
Why is capacitive reactance negative?
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.
What is the applied voltage to a resistive capacitive circuit?
this is the amount of voltage a circuit can hold.
What is the relationship between the current and the components in a purely capacitive circuit?
In a purely capacitive circuit, the current and the components have a relationship where the current leads the voltage by 90 degrees. This means that the current and voltage are out of phase in a purely capacitive circuit.
In a capacitive AC circuit the current is?
leading the voltage.
How many degrees are the current and voltage out of phase in a pure capacitive circuit?
In a pure (ideal) capacitive circuit, current leads voltage by 90 degrees.
What happens to current flow in a capacitive circuit in comparison to voltage?
The current leads the voltage by 90degree....
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.
A circuit with a lagging current means the circuit is?
Inductive. Voltage (E) leads current (I) in an inductive (L) circuit and current (I) leads voltage (E) in a capacitive (C) circuit. (ELI the ICEman)
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.
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 it mean to say that an alternating current leads or lags an alternating emf?
It is another way of saying that the circuit is capacitive reactive circuit. Look up the mnemonic ELI the ICE man. ELI, voltage leads the current in an inductive circuit. ICE, current leads the voltage in a capacitive 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.
Will the source voltage lead or lag the current in a circuit?
In an AC circuit, the source voltage can either lead or lag the current, depending on the type of load. Inductive loads cause the voltage to lag the current, while capacitive loads cause the voltage to lead the current.
