DC Circuits Homework: Calculating Power & Resistance

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The discussion revolves around calculating the resistance of eight parallel-connected lights powered by a 119V source, with a total lead resistance of 2.5 ohms and a current of 240mA through each bulb. The initial calculations provided by a user were incorrect, as they misapplied the voltage and resistance formulas. To accurately determine the total resistance and power loss, it's essential to consider the lead resistance as a series component in the circuit. Participants suggest using Kirchhoff's laws and Ohm's law to clarify the circuit's behavior and correct the user's calculations. Understanding these principles is crucial for resolving the discrepancies in the homework problem.
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1. Eight lights are connected in parallel to a 119V source by two leads of total resistance 2.5 ohms. If 240mA flows through each bulb what is the resistance of each? What fraction of the total power is wasted in the leads?


2. V=IR, P=I^2(R)



3. V=.24(119)=495.83/8=62ohms
P=(.24)^2(62)=3.57W
These are the answers i got but according to my book they are wrong. Can anyone tell me what I am doing wrong? thanks
 
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Well as for your first question you seem to have V=iV.

Now you know the resistors are connected in parallel.

To find the total resistance of all components, add the reciprocals of the resistances R of each component and take the reciprocal of the sum. :D.
 
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2.5ohms is the total resistence? I thought that was just the resitence in the wire going from the battery and the wire going to the battery
 
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In addition to what you already know about the circuit, you need (well, I suggest):

1) An equivalent circuit where you include a 2.5 ohms series resistor to represent the loss in the wires.
2) Kirchoff's Current Law
3) Kirchoff's Voltage Law
4) Ohm's Law
5) The expression for power.

Use them in that order, and see how that goes.
 
what is Kirchoff's current law and voltage law? they're not in my book
 

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