Find total resistance in a network

In summary, the conversation is about a problem in a chapter that involves finding ##I_x## in a network. The person has tried using KCL and simplifying the components but is still struggling. They receive some hints and eventually solve the problem, obtaining a value of ##I_x = -1.5 mA##.
  • #1
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I can't get this last problem in the chapter. I am asked to find ##I_x## in the following network:

Screen Shot 2014-09-20 at 9.32.10 PM.png

My first hunch was to apply KCL to the node above the ##2I_x## source:

##10 + 2I_x - \frac{V}{2} - 3 + I_x + \frac{V}{5} + \frac{V}{10} = 0##

Where I have assumed the voltage ##V## is across all components in parallel. From here I've tried various things, but to no avail.
 
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  • #2
your v/5 term and your v/10 term add up to be Ix, but you've added them in again anyway. Not good.

can you compress the 10ma and 3ma sources down to one source and reduce all the resistors down to one resistor to get an expression for V that is only in terms of Ix and the total resistance?

That's probably too many hints already. You should be able to take it from there.
 
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  • #3
phinds said:
your v/5 term and your v/10 term add up to be Ix, but you've added them in again anyway. Not good.

can you compress the 10ma and 3ma sources down to one source and reduce all the resistors down to one resistor to get an expression for V that is only in terms of Ix and the total resistance?

That's probably too many hints already. You should be able to take it from there.

Thank you sir, every problem in chapter 2 is now complete (there was a lot in this chapter, > 100). I obtained ##I_x = - 1.5 mA##.

I can finally take it easy after all that, feels like an abyss in my brain right now. I owe you one.
 
  • #4
Zondrina said:
Thank you sir, every problem in chapter 2 is now complete (there was a lot in this chapter, > 100). I obtained ##I_x = - 1.5 mA##.

I can finally take it easy after all that, feels like an abyss in my brain right now. I owe you one.

Glad to hear it.
 
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  • #5


I understand your frustration and desire to solve this problem. However, without more context and information about the network, it is difficult for me to provide a specific solution. In order to find the total resistance in a network, we need to use Ohm's Law (V=IR) and Kirchhoff's Laws (KCL and KVL) to analyze the circuit and determine the equivalent resistance. It is important to also consider the type of network (series, parallel, or combination) and the values of the resistors in order to determine the most effective method for solving the problem. I suggest reviewing these concepts and carefully examining the given network to see if there are any patterns or simplifications that can be made to make the problem more manageable. Additionally, seeking help from a classmate, teacher, or online resources may also be helpful in finding a solution. Keep in mind that problem-solving in science often requires persistence and creativity, so don't give up and keep experimenting with different approaches until you find the answer.
 

1. How do I calculate total resistance in a network?

To calculate the total resistance in a network, you can use Ohm's Law, which states that resistance (R) equals voltage (V) divided by current (I). In a series circuit, you can add the individual resistances together to find the total resistance. In a parallel circuit, you can use the formula 1/Rt = 1/R1 + 1/R2 + 1/R3... where Rt is the total resistance and R1, R2, R3, etc. are the individual resistances.

2. What is the unit of measurement for resistance?

The unit of measurement for resistance is ohms (Ω). This is named after the German physicist Georg Ohm, who first described the relationship between voltage, current, and resistance.

3. Does the placement of resistors in a circuit affect the total resistance?

Yes, the placement of resistors in a circuit can affect the total resistance. In a series circuit, the resistors are placed one after the other, so the total resistance is the sum of all the individual resistances. In a parallel circuit, the resistors are placed next to each other, so the total resistance is less than the smallest individual resistance.

4. Can the total resistance in a network ever be zero?

No, the total resistance in a network cannot be zero. This is because any circuit will have some amount of resistance, even if it is very small. In a parallel circuit, the total resistance can approach zero as more resistors are added, but it will never be exactly zero.

5. How can I measure the total resistance in a circuit?

You can measure the total resistance in a circuit using a multimeter. Set the multimeter to the resistance (Ω) function and then touch the probes to the two ends of the circuit. The multimeter will display the total resistance in ohms. Alternatively, you can calculate the total resistance using the methods mentioned in the first question.

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