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Question
1. what component causes total power dissimination in an rl series circuit?

2. in ac circuits, what are powers normally associated with?

3. how does reactive components like inductors and capacitors affect the over all power factor of an ac circuit?

4. how is maximum power transfer attained in ac circuits?

5. in most industrial loads, how are the power factors corrected in order to maximize power consumption?

Answer
1. In any electric circuit, ac or dc, only the resistive elements dissipate power.  Reactive elements, L and C, only let current pass but they do not dissipate power - in the ideal sense - in reality an inductor has some resistance due to the wires of the coil and therefore the resistance of the coil will dissipate power.  But for theoretical analysis we normally think of the ideal coil/inductor with zero resistance - or bring it outside the coil and show it as a resistor.

2. As above, any resistive component will dissipate power (heat) when current is passing through.  Power = current times voltage  or P = ExR.

3. Power factor is the cosine of the angle. If the reactive components change the phase of the circuit then  the power factor is changed as well.  

4. Maximum power transfer is when the power factor is pure resistive and the phase angle is zero degrees.

5. Power factor can be corrected by adding into the circuit a reactive component to correct the phase angle.  For example in electric motors it is often necessary to add a capacitor to offset the high inductance of the motor windings.  And so on.

Ok? Hope this helps.  

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Electronics questions about AC, DC and digital theory.

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Graduate electrical engineer with over 40 years in electronic design, manufacturing, project organization and patent review. Experience in fields of industrial and consumer electronics (audio, video, acoustics, etc.)

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IEEE (Institute of Electrical and Electronics Engineers); Senior Life member AES (Audio Engineering Society), Fellow Life member

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BSEE University of North Dakota

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