Effective resistance between two points

In summary, the conversation is about identifying whether resistors in a circuit are in parallel or series and how to calculate the effective resistance. The person is having trouble understanding how to identify parallel resistors from a diagram and asks for help. A rule is given to determine if elements are in series or parallel and it is confirmed that this method works for any resistor circuit.
  • #1
DarylMBCP
90
0
Hey guys, I'm having a little troublt with rearranging resistors in a circuit to identify which are parallel and which are in series so I can decide how they should be added; RTotal = R1 + R2 or RTotal = 1/R1 + 1/R2.

Taking that each of the three resistors in the circuit shown (diagram attached) has a resistance of 6 ohms, what is the effective resistance between X and Y? The answer key shows that the three are parallel and if that is so, I knw how to calculate the effective resistance to get 2 ohms.

However, I'm not sure how to identify if they are parallel or not from the diagram. Any help is greatly appreciated. Thanks.
 

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  • #2
One little rule to make that decision is this: series elements have the same current, while parallel elements have the same voltage difference.
 
  • #3
One little rule to make that decision is this: series elements have the same current, while parallel elements have the same voltage difference.

Ok, so from the diagram I can see that the three resistors have different current passing through them but have the same voltage difference so the MUST be parallel, right? Is this method standard for all examples? Thanks for the help.
 
  • #4
Yes, same voltage means they are in parallel. And I'm pretty sure this method does work for any resistor circuit.
 

1. What is the definition of effective resistance between two points?

The effective resistance between two points is a measure of the total resistance encountered by an electric current traveling from one point to another in a circuit. It takes into account the resistance of all components, such as wires and resistors, between the two points.

2. How is the effective resistance calculated?

The effective resistance is calculated using Ohm's Law, which states that resistance is equal to the voltage difference between two points divided by the current flowing between them. It can also be calculated using Kirchhoff's Laws, which take into account the total current and voltage in a circuit.

3. Why is the effective resistance important in circuits?

The effective resistance is important because it determines the amount of current that can flow between two points in a circuit. It also affects the overall efficiency of the circuit and can help in determining the appropriate components to use in a circuit design.

4. How does the effective resistance change in series and parallel circuits?

In a series circuit, the effective resistance is equal to the sum of all individual resistances. In a parallel circuit, the effective resistance is less than the smallest individual resistance. This is because in a parallel circuit, there are multiple paths for the current to flow, reducing the overall resistance.

5. Can the effective resistance ever be negative?

No, the effective resistance cannot be negative. Resistance is a measure of how much a material or component resists the flow of current, so it cannot have a negative value. If calculations result in a negative resistance, it is likely an error in the circuit or equations being used.

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