Can self induction increase power consumption?

AI Thread Summary
The discussion revolves around the power consumption differences of a coil when subjected to direct current (DC) versus alternating current (AC). A coil made of copper wire showed a power consumption of 5W under DC and 5.5W under AC, while a straight wire under AC returned to 5W. The user speculates that in a DC regime, the coil behaves like a short circuit over time, while AC induces self-induction, requiring higher voltage to maintain the same current. Questions about the coil's inductance, frequency, and measurement methods were raised, indicating a need for more precise data to understand the observed power variations. Overall, the conversation highlights the complexities of power consumption in different electrical regimes.
Jucimar
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Hi folks,

My question relays on the difference of consumption power of a coil when it's on AC and CC regime.

A coild is made of copper wire with air core, aplied on it a CC current of 1 amp, a measure was taked and nottice a 5W of power consumption. Then the power supply is changed to and AC power suplly, now the consumption was about 5,5W. Now the coil was dismaid and it is just a simple wire ( straigh line) and remais on AC power supply. Now the consumption is around 5W again.I have some tought about it but I'm not quite sure. It seems to me that when you a CC regime on a wire, the coil only represent a indcutor it self and after a long time it turn just to be a short circuit, so this can't increase the power.
When i have the coil on AC regime, it creates a self induction made by a opsition to the real currente that pass trough the wire, in that, we need to increase the voltage of the power supply to still with 1 amp (effective).

Can someone help me to understand why this occurs?
 
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Jucimar said:
CC

Do you mean DC?
 
anorlunda said:
Do you mean DC?

Yes, CC for me in Brazil is "Continuos Current" or in USA Direc Currente.
 
Jucimar said:
Then the power supply is changed to and AC power suplly, now the consumption was about 5,5W.
Welcome to the PF.

Do you know what the inductance was of the coil? What frequency was the AC applied? How were you measuring the current and voltage and power? What DC and AC voltages were used? What were the sources of those voltages?
 
berkeman said:
Welcome to the PF.

Do you know what the inductance was of the coil? What frequency was the AC applied? How were you measuring the current and voltage and power? What DC and AC voltages were used? What were the sources of those voltages?

The statement was made in a exam of my college...this data was all about we had...when you do some calculus by ohms law we can see the dc voltage is 5 volts, perhaps that on ac voltage its no simple, the frequency is 60hz... so my think is that to maintain the same currente of 1 amp (effective current) the only when to increase power is to increase ac voltage, makes any sense for you?
 
Power dissipation given the same DC and RMS voltage should be the same. The question is not well-formed, IMO.
 

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