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Because in an AC circuit, a capacitor opposes the change of voltage in at. At the peak of the voltage waveform, there is no change (it is nearly flat), so at this same point in time, the current waveform is at zero.
Likewise, when the voltage waveform crosses zero, it is changing at its fastest rate, so the current is at its peak.
If you draw these two waveforms next to one another, you will see the voltage has the appearance of being behind the current - hence the term 'lag'.
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∙ 13y ago
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∙ 14y agoCurrent lags behind voltage when the load is inductive. With a capacitive load, the opposite is true, with the voltage lagging behind the current, or the current leading the volage. (However you want to say it)
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∙ 13y agodue to current drawn to supply the inductive load for creating magnetic flux.This is represented in kvar which makes lagging power factor
possibly due also to the resultant flux opposing the direction of the current in the circuit.
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∙ 14y agoCurrent lags behind voltage when there is inductive reactance in the circuit. Inductors resist a change in current, by appearing to have higher resistance when the voltage suddenly changes.
This lag complicates the calculation of power, because now you need to consider phase angle as it relates to volts-amps reactive, volt-amps non reactive, power factor, watts, etc.
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∙ 14y agoCapacitors are reactive elements, which means that do not use energy, but store it for a time, then release it. This storing and releasing is what causes the current to lag.
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Don't think it does. I have always used Eli the Ice man. Current lags the voltage in an inductive circuit and voltage lags the current in a capacitive circuit.
Woodman66 is right. A capacitor's impedance = 1/(jwC), and I = V/R:
I = V / (1/jwC) = j*(V*w*C). the 'j' is an imaginary number representative of a 90 degree phase shift. So when voltage is at 0 degrees, current will be at 90 degrees, or leading.
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∙ 12y agoThe voltage induced into a coil opposes the supply voltage and is proportional to the rate of change of current. The greatest (positive) rate of change of current occurs when the current waveform is at its steepest -i.e. as it passes through the zeros axis. At this point, the induced voltage is at its maximum value and is equal but opposite to the supply voltage. So the current must then reach its peak 90 electrical degrees later -in other words, it lags the supply voltage by 90 degrees (for a pure inductance).
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∙ 16y agoInductive circuit..remember ELI the ICE man, E=voltage, I=current, L=inductance, C=capacitance
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∙ 11y agoreactance of circuit
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What cause the voltage t lead current in an ac circuit?
Voltage leads current or, more specifically current lags voltage, in an inductive circuit. This is because an inductor resists a change in current.
How current lags the voltage in inductor?
In a perfect inductor (one with no series internal resistance), the current lags the voltage by 90 degrees. If the inductor has series internal resistance, then the current will lag the voltage by less than 90 degrees - the more the resistance in series with the inductor, the smaller the angle. The tangent of the angle can be found from the ratio of the inductive reactance of the inductor to the DC resistance of the inductor. That is, Tan (phase angle) = (2 x pi x frequency (Hz) x inductance (H)) divided by resistance (ohms) eg, a 1 henry, 100 ohm inductor on 60Hz would give: (2 x pi x 60 x 1) / 100 = 3.77; tan-1(3.77) gives 75 degrees lag of current behind voltage. The cosine of this angle gives the 'power factor' for the inductor - that is, the amount of useful energy dissipated in the inductor. Cos 75 is about 0.25 - so 25% of the energy actually does useful work (heat) - the rest of the energy (75%) is returned to the supply mains when the inductor discharges its magnetic field.
What is the power factor of an induction motor?
Induction motor comprised inductor as the most part in it and an inductor has the characteristic to oppose the change of current, i.e., it has lagging power factor as current lags behind the voltage. Hence, an induction motor works on lagging power factor.
What is the meaning of current lags voltage?
'Current lags voltage' means that in the AC cycle the voltage peaks and the current peaks a little time (a fraction of a cycle) later. This happens with electrical loads like motors. When the current lags, there is a small period in each half-cycle when the voltage has reversed and the current has not reversed yet. This causes power to flow back into the supply from the load. So there is a loss of average power fed to the load for a given voltage and current. In this situation the power is the voltage times the current times the power factor, and the power factor is the cosine of the angle by which the current lags the voltage (counting 360 degrees as a full cycle).
What is the reason behind the lag of current in inductor lead in capacitor?
The physics of the energy storage. In an inductor, the current must fight against the stored energy in the magnetic field which tries to keep the current unchanged. Any change in the current lags the voltage since the stored energy impacts the adjustment. Similarly, the "displacement" current in a capacitor leads the electric field buildup in a capacitor, causing the voltage to lag the current until the stored energy building up in the electric field stabilizes. Any change in the voltage is first preceded by a change in the displacement current.
What is the bahaviorS of the INDUCTOR in ac supply?
Because of Ac supply, current lags voltage by 90 in Inductor.
What cause the voltage t lead current in an ac circuit?
Voltage leads current or, more specifically current lags voltage, in an inductive circuit. This is because an inductor resists a change in current.
What is the phase angle between voltage and current in a purely capacitive circuit?
Current leads voltage (or voltage lags current) by 90° in a purely capacitive circuit. Try to remember it this way: capacitors resist change in voltage, hence the voltage lags (they resist voltage change because the voltage first goes to charging up the electric field in the capacitor).Inductors resist change in current (energy in an inductor is in the form of magnetic fields, which are caused by the current through the wire). Remember an inductor is a coil (like an electromagnet, or a transformer).
Is there no induced voltage in an inductor unless the current is changing?
In an ideal inductor, no, there is no voltage induced across an inductor unless the current in the inductor is changing. However, since there are no ideal inductors nor power supplies, eventually an inductor will draw a constant current, i.e. the limit of the power supply; and, since no inductor has zero ohms at equilibrium, that current will translate to voltage.
How current lags the voltage in inductor?
In a perfect inductor (one with no series internal resistance), the current lags the voltage by 90 degrees. If the inductor has series internal resistance, then the current will lag the voltage by less than 90 degrees - the more the resistance in series with the inductor, the smaller the angle. The tangent of the angle can be found from the ratio of the inductive reactance of the inductor to the DC resistance of the inductor. That is, Tan (phase angle) = (2 x pi x frequency (Hz) x inductance (H)) divided by resistance (ohms) eg, a 1 henry, 100 ohm inductor on 60Hz would give: (2 x pi x 60 x 1) / 100 = 3.77; tan-1(3.77) gives 75 degrees lag of current behind voltage. The cosine of this angle gives the 'power factor' for the inductor - that is, the amount of useful energy dissipated in the inductor. Cos 75 is about 0.25 - so 25% of the energy actually does useful work (heat) - the rest of the energy (75%) is returned to the supply mains when the inductor discharges its magnetic field.
Why voltage leads current in a inductor?
Eli the ice man. Voltage (E) before Current (I) in a coil (inductor)(L) Current (I) before Voltage (E) in a Cap. (C) Got it?
What is the power factor of an induction motor?
Induction motor comprised inductor as the most part in it and an inductor has the characteristic to oppose the change of current, i.e., it has lagging power factor as current lags behind the voltage. Hence, an induction motor works on lagging power factor.
What does the voltage across a inductor do?
voltage across inductor create a flux. because of variation current developes an opposite emf.
What is the meaning of current lags voltage?
'Current lags voltage' means that in the AC cycle the voltage peaks and the current peaks a little time (a fraction of a cycle) later. This happens with electrical loads like motors. When the current lags, there is a small period in each half-cycle when the voltage has reversed and the current has not reversed yet. This causes power to flow back into the supply from the load. So there is a loss of average power fed to the load for a given voltage and current. In this situation the power is the voltage times the current times the power factor, and the power factor is the cosine of the angle by which the current lags the voltage (counting 360 degrees as a full cycle).
What is the maximum inductor voltage when the inductor current is decreasing?
depending on the stray capacitance it can be from a few ten volts to a few kilo volts.
What components comprise the excitation current of a transformer?
A transformer's excitation current can be resolved into two components. The first is in phase with the primary voltage, and is responsible for the losses. The second lags the supply voltage by 90 degrees, and is responsible for magnetising the core.
Why current lead voltage in coil?
because a coil is an inductor,for current leads voltage in an inductorAnswerIt doesn't! Current lags voltage in a coil. In a purely-inductive circuit, the current lags the supply voltage by 90 degrees. The reason for this is 'self inductance'. Whenever a current changes, a voltage is induced into the coil which opposes that change in current. The maximum self-induced voltage occurs when the rate of change in current is greatest. The greatest positive rate of change of a.c. current occurs when that current is passing through the zero axis of its waveform, so the greatest (negative) induced voltage occurs at thatsame point, which is one-quarter of the wavelength, or 90 degrees. In accordance with Kirchhoff's Voltage Law, the supply voltage must be in antiphase with the induced voltage. So when the peak induced voltage is negative, the peak applied voltage must be positive. Or, to put it another way, the peak value of the applied voltage must occur 90 degrees before the peak value of the current -so the current lags the applied voltage by 90 degrees.
