In electrical science what are the apparent power , active power and reactive power ?

actually it depends on the nature of circuit components .. and regarding the generation it depends on the inputs to the generation systems whether the steam or the field  .. so that on the relation between the circuit voltage and current waveforms .. so it can be easily to figure out the nature ,formula ,and the difference between  each power once when drawing the current & voltage waveform for different loads resistor , inductive and capacitive as well . power = waveform of voltage * waveform of current for resistor loads the power in all cycles will be positive so it is given power consumed so u can name it as active power .for capacitive or inductive loads the power will be the same magnitude with different sign each1/4 of  the cycle it fluctuated between the source and the load it return back to the source again and again so we can name it as reactive power .what about if the circuit components are all these loads ?  both active and reactive power would appear in the circuit .and the angle between current and voltage will be between0 and degree as u see it is not just values but values and angles so the total power will the vector summation of  both act.and react. powers .u can deduce different formula to represent the upper relation for example:apparent power = active power /cos(the angle between V and I waveforms ) apparent power=reactive power/sine (the angle )cos(the angle) is called as the power factor or the load factor as u see it depends on the nature of  loads ... in other words for the circuit supplied by AC source to incandescent lamp ,the power factor is1 as the the angle between v and current waveforms for this load is nothing .. so for this load the reactive power would be nothing as well , the total apparent power will be equal to the active power .

Active Power:

The power which is consumed by load .It measures in KW

Reactive Power:

the power which is required for excitation of components like capacitor , inductor. it is measures in kvar

Apparent Power :

the total power (reactive +active ) is called apparent power .it is measures in Kva

Apparent power =Active power+Reactive power

Kva=KW+Kvar

Apparent power is In an AC circuit, the product of the rms voltage and the rms current . When the impedance is a pure resistance, the Apparent power is the same as the true power. But when reactance exists, the apparent power is greater than the true power.but We know that reactive loads such as inductors and capacitors dissipate zero power, yet the fact that they drop voltage and draw current gives the deceptive impression that they actually do dissipate power. This “phantom power” is called reactive power

Thank you for your invitation. I agree with Mr. Karthi's answer as he has explained the Apparent power, Active power & Reactive power in detail.

apparent power is the sum of the active and the reactive power measured in volt-amperes (VA) S=IZ

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active power is the real power that does actual work, it is measured in watts (W) P=I^2 R

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reactive power or reactive inductive power which is the stored power Q=S sinφ it measured in Volt-Amps-Reactive (VAR)

I apologize I am civil eng.

• Total power in an AC circuit, both dissipated and absorbed/returned is referred to as apparent power. Apparent power is symbolized by the letter S and is measured in the unit of Volt-Amps (VA).
• Power dissipated by a load is referred to as Active power. Active power is symbolized by the letter P and is measured in the unit of Watts (W).
• Power merely absorbed and returned in load due to its reactive properties is referred to as reactive power. Reactive power is symbolized by the letter Q and is measured in the unit of Volt-Amps-Reactive (VAR).

Power triangle relating appearant power to true power and reactive power.

Apparent Power = Sq. rt (Active Power^2 + Reactive Power^2)=VI

Active Power = V*I*Cos(theta)

Reactive Power = V*I*Sin(theta)

True Power: is the power being used or dissipated in resistive element.

Reactive Power: is the power being stored and returned by reactive element.

Apparent Power: is the combination of the both True and Reactive power. It is also the product of the RMS values of Voltage and Current.