airs of parallel wires or coaxial cables are two conductors separated by an insulator, so they have a capacitance. For a given cable, the capacitance is independent of the length if the cable is very long. A typical circuit model of a cable is shown in the figure below. It alled a lumped-parameter model and represents how a unit length of the cable behaves. Find the equivalent capacitance of the following lengths. (Use the following as necessary: C.) C C2 A. One unit length B. Two unit lengths 00 C C. Infinite number of unit lengths (a) one unit length (Figure A) CC C+C (b) two unit lengths (Figure B) ССС C2 CC (c) an infinite number of unit lengths (Figure C). Hint: For the infinite number of units, adding one more unit at the beginning does not change the equivalent capacitance. Coo = 0.618c
Pairs of parallel wires or coaxial cables are two conductors separated by an insulator, so they have a capacitance. For a given cable, the capacitance is independent of the length if the cable is very long. A typical circuit model of a cable is shown in the figure below. It is called a lumped-parameter model and represents how a unit length of the cable behaves. Find the equivalent capacitance of the following lengths. (Use the following as necessary: C.)
(a) one unit length (Figure A)
(b) two unit lengths (Figure B)
(c) an infinite number of unit lengths (Figure C). Hint: For the infinite number of units, adding one more unit at the beginning does not change the equivalent capacitance.
C∞ =

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\[ C_1 = \frac{CC}{C + C} \]
- In Figure A, the single unit length of the cable is modeled with two capacitors \( C \) in series, resulting in an equivalent capacitance \( C_1 \).
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**B. Two unit lengths**

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\[ C_2 = \frac{CC}{C + C} \]
- In Figure B, two unit lengths of the cable are considered. Although two unit lengths are modeled, the equation given under (b) is incorrect. A proper series and parallel combination analysis should be conducted for an accurate equivalent capacitance.
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**C. Infinite number of unit lengths**

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\[ C_{\infty} = 0.618C \]
- In Figure C, an infinite number of unit lengths are represented by a repeating pattern of capacitors \( C \). For an infinite series of unit lengths, adding one more unit at the beginning does not alter the equivalent capacitance. The equivalent capacitance for an infinite number of units, \( C_{\infty} \), is approximately \( 0.618C \), though further verification is required since the equation under (c) is marked as incorrect.
### Summary
Understanding the equivalent capacitance in different cable lengths aids in the design and analysis of electrical systems where such configurations are in use. Here's how you can compute the capacitance for one unit length, two unit lengths (with correct calculations), and an indefinite length systematically.
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For further reading, ensure you reference your circuit theory textbooks or reliable resources to verify complex calculations.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F188f854e-5fc6-4301-8b8b-5d31fc4cc5e7%2Fdce86819-c2e3-49dd-8863-1d7bf1512bdc%2Fs177pik.png&w=3840&q=75)

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