Difficult : Calculate equivalent resistance of the circuit problem .

In summary, the two straight 1 ohm resistors are in parallel, giving 1*1/1+1= 1/2 resistance. The two resistors in series give 2 resistance, then the two resistors in parallel give 1 resistance. The answer is 1.75 ohms.
  • #1
agoogler
81
0

Homework Statement



Calculate the total equivalent resistance between A and D -
r8ibJ.png

( All resistors are 1 ohm )

Homework Equations


-


The Attempt at a Solution


The only thing I can see is that the two straight 1 ohm resistors are in parallel , giving 1*1/1+1= 1/2 resistance. But what next , please help !
 
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  • #2
agoogler said:

Homework Statement



Calculate the total equivalent resistance between A and D -
r8ibJ.png

( All resistors are 1 ohm )

Homework Equations


-


The Attempt at a Solution


The only thing I can see is that the two straight 1 ohm resistors are in parallel , giving 1*1/1+1= 1/2 resistance. But what next , please help !

It's not clear what you mean by "the two straight 1 ohm resistors", but try this...

Since B and C are open circuits for this question, delete their respective 1 Ohm resistors. Then re-draw the circuit, with A at the top and D at the bottom. See if you can draw the resistors in a more normal configuration, using this simplification...
 
  • #3
The only thing I can see is that the two straight 1 ohm resistors are in parallel , giving 1*1/1+1= 1/2 resistance.

There are no resistors directly in parallel so the above can't be right.

Do what berkeman said.
 
  • #4
berkeman said:
It's not clear what you mean by "the two straight 1 ohm resistors", but try this...

Since B and C are open circuits for this question, delete their respective 1 Ohm resistors. Then re-draw the circuit, with A at the top and D at the bottom. See if you can draw the resistors in a more normal configuration, using this simplification...
Okay.
After deleting those two , I can see two pairs of resistors in series giving 2 each. Then these two 2 ohm resistors are in parallel , giving 1 ohm. Now these is in series with the remaining two 1 ohm resistors giving 3 ohm as the answer. Am I correct ?
 
  • #5
I am sure that you are correct.
 
  • #6
I agree.
 
  • #7
According to Wheatstone bridge
Answer is 7/4 ohms that is 1.75 ohms
Am I correct ?
 
  • #8
Kabir Nanda said:
According to Wheatstone bridge
Answer is 7/4 ohms that is 1.75 ohms
Am I correct ?
No. Show your work. Or better yet, start a new thread since this is a rather old thread (from 2013) and the Original Poster hasn't been logged in since 2015.
 

1. How do I calculate the equivalent resistance of a circuit?

To calculate the equivalent resistance of a circuit, you need to first identify all the resistors in the circuit. Then, you can use the formula Req = R1 + R2 + ... + Rn to find the sum of all the resistors' values. This will give you the equivalent resistance of the circuit.

2. What is the purpose of calculating equivalent resistance?

Calculating equivalent resistance allows you to simplify a complex circuit into a single resistor, making it easier to analyze and understand the behavior of the circuit. It also helps in determining the overall resistance of a circuit, which is important in designing and troubleshooting electronic systems.

3. Can I use the same formula to calculate equivalent resistance for both series and parallel circuits?

No, the formula for equivalent resistance is different for series and parallel circuits. For series circuits, the equivalent resistance is simply the sum of all the resistors' values. For parallel circuits, the formula is 1/Req = 1/R1 + 1/R2 + ... + 1/Rn.

4. How do I know which resistors are in series and which are in parallel?

In a series circuit, the resistors are connected in a single path, while in a parallel circuit, they are connected in multiple paths. You can also use the rule that resistors in series have the same current flowing through them, while resistors in parallel have the same voltage across them.

5. Can I use the equivalent resistance to calculate the current and voltage in a circuit?

Yes, the equivalent resistance can be used to calculate the current and voltage in a circuit. In a series circuit, the current is the same throughout, so you can use Ohm's law (V = IR) to find the voltage across the equivalent resistance. In a parallel circuit, the voltage is the same across each resistor, so you can use Ohm's law to find the current through the equivalent resistance.

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