Math Problem Statement

Find The equivalent resistance between terminals A and B for the network shown in Figure below

Find the equivalent resistance between terminals A and B for the network shown in Figure.

Solution

To find the equivalent resistance between terminals AA and BB for the given network, we need to follow systematic steps involving combination of resistors, both in series and in parallel. The key is identifying how resistors are connected across various points.

Steps:

  1. Simplify Parallel and Series Combinations:

    • Start by identifying resistors that are clearly in series or parallel and reduce them step by step.
  2. Look at Series and Parallel Combinations in Different Sections:

    • The two resistors labeled 3Ω3 \, \Omega between GG and FF and between FF and DD are in series, so their combined resistance is: RGF=3Ω+3Ω=6Ω.R_{GF} = 3 \, \Omega + 3 \, \Omega = 6 \, \Omega.

    • Now, the 6Ω6 \, \Omega (from GFGF) is in parallel with the 1Ω1 \, \Omega resistor between FF and EE. The combined resistance of two resistors in parallel is given by: 1Rparallel=1R1+1R2.\frac{1}{R_{\text{parallel}}} = \frac{1}{R_1} + \frac{1}{R_2}. Substituting values for the 6Ω6 \, \Omega and 1Ω1 \, \Omega resistors: 1Rparallel=16+11=1+66=76,\frac{1}{R_{\text{parallel}}} = \frac{1}{6} + \frac{1}{1} = \frac{1 + 6}{6} = \frac{7}{6}, so Rparallel=67Ω0.857Ω.R_{\text{parallel}} = \frac{6}{7} \, \Omega \approx 0.857 \, \Omega.

  3. Combine with Series Resistor:

    • Now, this 0.857Ω0.857 \, \Omega is in series with the 3Ω3 \, \Omega resistor between GG and CC, so the total resistance between CC and DD becomes: RCD=3Ω+0.857Ω3.857Ω.R_{CD} = 3 \, \Omega + 0.857 \, \Omega \approx 3.857 \, \Omega.
  4. Parallel Between CC and DD and the Rest of the Network:

    • Now, look at the two resistors connected between CC and DD: one is 3.857Ω3.857 \, \Omega and the other is 1Ω1 \, \Omega. These two resistors are in parallel, so their combined resistance is: 1Rtotal=13.857+11.\frac{1}{R_{\text{total}}} = \frac{1}{3.857} + \frac{1}{1}. Calculating the parallel combination: 1Rtotal=13.857+11.259,\frac{1}{R_{\text{total}}} = \frac{1}{3.857} + 1 \approx 1.259, so Rtotal0.794Ω.R_{\text{total}} \approx 0.794 \, \Omega.
  5. Combine with Rest of the Circuit:

    • The Rtotal0.794ΩR_{\text{total}} \approx 0.794 \, \Omega is in series with the 8Ω8 \, \Omega resistor between AA and CC, giving the total resistance between AA and DD: RAD=8Ω+0.794Ω8.794Ω.R_{AD} = 8 \, \Omega + 0.794 \, \Omega \approx 8.794 \, \Omega.
  6. Final Parallel with 7.6Ω7.6 \, \Omega Resistor:

    • Lastly, the combined RAD8.794ΩR_{AD} \approx 8.794 \, \Omega is in parallel with the 7.6Ω7.6 \, \Omega resistor between AA and BB. Applying the parallel resistor formula: 1Req=18.794+17.6,\frac{1}{R_{\text{eq}}} = \frac{1}{8.794} + \frac{1}{7.6}, we calculate: 1Req=0.1137+0.13160.2453,\frac{1}{R_{\text{eq}}} = 0.1137 + 0.1316 \approx 0.2453, so Req=10.24534.08Ω.R_{\text{eq}} = \frac{1}{0.2453} \approx 4.08 \, \Omega.

Final Answer:

The equivalent resistance between terminals AA and BB is approximately 4.08Ω\boxed{4.08 \, \Omega}.

Would you like a more detailed breakdown of any specific step?


5 Related Questions:

  1. What is the difference between resistors in series and parallel?
  2. How does one calculate the total resistance of multiple resistors in parallel?
  3. What happens to the overall resistance if resistors of unequal values are connected in parallel?
  4. How can the Wheatstone Bridge principle simplify circuits like this one?
  5. How would adding another resistor between points CC and DD affect the overall resistance?

Tip:

Always look for resistors in series or parallel first to simplify complex circuits step by step!

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Math Problem Analysis

Mathematical Concepts

Resistor Networks
Series and Parallel Circuits

Formulas

Series Resistance: R_total = R1 + R2
Parallel Resistance: 1/R_total = 1/R1 + 1/R2

Theorems

Ohm's Law
Resistor Combination Theorem

Suitable Grade Level

Grades 10-12