How Much Power Does Each Resistor Dissipate?

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Homework Help Overview

The discussion revolves around calculating the power dissipated by two resistors, specifically a 12Ω and an 18Ω resistor, in a given circuit. Participants are exploring the application of Ohm's law and power equations in this context.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the need to find the voltage drop across the resistors and the current in the circuit. There are attempts to derive the power using different equations, including P=IV and P=I²R. Some participants express confusion regarding the current values provided in the problem.

Discussion Status

The discussion is ongoing, with participants providing hints and suggestions for finding the necessary values to calculate power. There is recognition of the need to clarify the current in the circuit and the voltage across the resistors, but no consensus has been reached on the correct approach or values.

Contextual Notes

Participants note that the problem only provides limited information, which may affect their calculations. There is mention of needing to create an equivalent resistance for the circuit to find the current.

cwesto
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Homework Statement



How much power is dissipated by the 12[tex]\Omega[/tex] resistor in the figure?
32.jpg

PR1=______W
How much power is dissipated by the 18 resistor in the figure?
PR2=______W

Homework Equations



P=IV
I=[tex]\frac{V}{R}[/tex]

The Attempt at a Solution



P=[tex]\frac{V}{R}[/tex]*V
P=V2/R

P=12*12/12=12V

After solving for my equation I plugged in my numbers but it's not correct. All I need are a few hints to lead me in the right direction. Thanks!
 
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Please show the details of your calculations so we can see what you're doing. You need to find the voltage drop across the resistor you're interested in. Note this will NOT be 12V.
 
Try finding either the current through the resistors or the voltage across the resistors.
 
What is the current in the circuit?

The power is

P=RI^2

Where R is the resistanse of the component and I is the current through the component
 
the current is 2 amps. what is the equation to find the voltage drop?
 
It's Ohm's law. But all you need is the current. Try arrangin the power equation so that you only need to use the current and resistor. Is that the current for the whole circuit? If so it's incorrect.
 
wait sorry they don't give the current my bad. i was looking at another problem. sorry
all the information up there is what they give me to solve the problem, nothing more.
 
cwesto said:
all the information up there is what they give me to solve the problem, nothing more.

You can find the current using the information in the problem. Okay, you know Ohm's law and you probably can create an Req for the two resistor in the circuit. That's should be enough to find the current.
 
So I found the power in each resistor using P=I^2R, plugging in the current going through that resistor and the resistance and I get the sum of the power being 204 watts. This is not what I got in part c. Is it supposed to be?
 
  • #10
sweetdion said:
So I found the power in each resistor using P=I^2R, plugging in the current going through that resistor and the resistance and I get the sum of the power being 204 watts. This is not what I got in part c. Is it supposed to be?

Hello sweetdion,

I think you might have posted to the wrong thread. :biggrin:
 
  • #11
collinsmark said:
Hello sweetdion,

I think you might have posted to the wrong thread. :biggrin:

Haha, yes, thank you. :blushing:
 

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