Current in the curcuit from watts and volts

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Homework Help Overview

The discussion revolves around a circuit problem involving a 50 V battery and three resistors, each rated at 25 Watts. The configuration includes one resistor in series and two in parallel, with the goal of determining the current in the circuit.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to find the equivalent resistance using power and voltage relationships but expresses confusion regarding the application of power ratings. Other participants suggest calculating the total power drawn from the battery and working through the implications for current and resistance.

Discussion Status

Participants are actively engaging with the problem, with some offering guidance on how to approach the calculations related to power and current. There is a recognition of the need to clarify the relationship between power, current, and resistance, but no consensus has been reached on a specific method or solution.

Contextual Notes

There is an emphasis on understanding the implications of the power ratings of the resistors and the overall current drawn from the battery. The original poster notes urgency in resolving their confusion, indicating a time constraint in their homework context.

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Homework Statement



A circuit has a 50 V battery, and 3 resistors. they are all 25 Watts, 1 is in series, 2 are parallel. Find the current of the circuit.

Homework Equations



V=IR
P=IV

The Attempt at a Solution



I know how to do these fine when I'm given the resistances or the amperages, but I'm having problems with this style.

I've attempted this a few different ways. I tried to find the equalizing resistance using: P=v^2/R
25=50^2/R
R=100 ohms.

then 1/100 + 1/100 = 1/Rparallel = 50. 50+100=150. to find the equalizing resistance, and then using:
V=IR
120=I*150
I= .8 Amps.

I'm clearly missing something when I'm working with Watts... can someone please walk me through how to actually do this. it's very urgent...
 
Last edited:
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The 3 resistors together use 25 + 25 + 25 = 75 watts.

This must come from the battery, so how much current is being drawn?

After that it is easy.

Work out each resistor knowing the power in it and the current (P=I*I*R). The two in parallel have the same resistance but you need to see why this has to be the case.
 
thanks
 
Actually, the question doesn't ask for the size of the resistors or the voltage across them. But it would be excellent practice for you to work them out.
They come out easily.
 

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