 What is the lead and lag of voltage current|Any fool can understand it - knoweasy

# What is the lead and lag of voltage current|Any fool can understand it

July 14, 2021

Because of the Sin (cot) can appear after the derivative or the integral Sin [ot + 909], so for inductor, capacitor connected to a sine wave, the abscissa to t can lead lag phenomenon observed waveforms, directly from the point of view of static function diagram are not well understood, or animation is better.

Below is the electric pulse, said voltage in red, blue electric current. If the ideal dc voltmeter, dc ammeter is connected, you can observe the change ahead of current, voltage changes in current lags behind the voltage. Time increases, the longitudinal axis and time of origin with the waveform moved to the left. If draw waveform in vector diagram to the right, which is the animation below, but here is the waveform of the existence of the past, pointing to the past, is - cot, although waveform, in turn, but the change of the voltage is still ahead of current, current changes still lags behind the voltage.

Time origin has been moved along with waveform to the right side, function diagram of longitudinal axis and horizontal is not in the origin, intersection represent time has been increasing. If you don't pay attention to, lead lag judgment error prone.

Understand the concept of lead lag with phasor diagram is the best, the observed from measurement data to or from the static wave observation are not very intuitive and easy to get wrong.

The figure below is capacitance. Voltage changes lags behind the current, current changes ahead of voltage. Coordinate system is the future, the left is the past.

when the abscissa is - wt, the change of capacitance voltage still lags behind the current, the current changes are still ahead of the voltage.Because of this coordinate system is left to the future, and to the right is the past.

The diagram below is resistive. The voltage function and the current function are in phase.

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