Why is the power consumed in ac circuits is zero?
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During half cycle, the capacitor gets charged. Here power is consumed by the circuit but in the next half cycle, the capacitor acts as the source of current rather than the cell as it is already charged by the first half cycle. Hence it is responsible to keep the circuit in "motion". During this discharge, it releases the energy it had and thus the power which was absorbed returns to the circuit. Hence in the total cycle the average power consumed is zero.
Note: This happens even with and inductor, resistance or their combination also. I have chosen capacitor here so as to explain more easily.
Note: This happens even with and inductor, resistance or their combination also. I have chosen capacitor here so as to explain more easily.
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AC circuits contain reactance, so there is a power component as a result of the magnetic and/or electric fields created by the components. The result is that unlike a purely resistive component, this power is not only consumed but instead is stored and then returned back to the supply as the sinusoidal waveform goes through one complete periodic cycle.
Thus, the average power absorbed by a circuit is the sum of the power stored and the power returned over one complete cycle. So a circuits average power consumption will be the average of the instantaneous power over one full cycle with the instantaneous power, p defined as the multiplication of the instantaneous voltage, v by the instantaneous current, i. Note that as the sine function is periodic and continuous, the average power given over all time will be exactly the same as the average power given over a single cycle.
AC circuits contain reactance, so there is a power component as a result of the magnetic and/or electric fields created by the components. The result is that unlike a purely resistive component, this power is not only consumed but instead is stored and then returned back to the supply as the sinusoidal waveform goes through one complete periodic cycle.
Thus, the average power absorbed by a circuit is the sum of the power stored and the power returned over one complete cycle. So a circuits average power consumption will be the average of the instantaneous power over one full cycle with the instantaneous power, p defined as the multiplication of the instantaneous voltage, v by the instantaneous current, i. Note that as the sine function is periodic and continuous, the average power given over all time will be exactly the same as the average power given over a single cycle.
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