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A wire of resistance \(9\text{ }\Omega\) is bent into the shape of an equilateral triangle. What is the equivalent resis…

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A wire of resistance \(9\text{ }\Omega\) is bent into the shape of an equilateral triangle. What is the equivalent resistance between any two vertices of the triangle?

(Shift I Memory Based)

a

\(1\text{ }\Omega\)

b

\(2\text{ }\Omega\)

c

\(3\text{ }\Omega\)

d

\(4\text{ }\Omega\)

✓ Correct answer: b)

\(2\text{ }\Omega\)

Explanation
  • Total resistance of the wire: \({R}_{\text{total}}=9\text{ }\Omega\)
  • Resistance of each side: \({R}_{\text{side}}=\frac{{R}_{\text{total}}}{3}=3\text{ }\Omega\)
  • Between any two vertices, there are two paths:
    1. Direct resistance \({R}_{1}=3\text{ }\Omega\).
    2. The other two sides (\({R}_{2}\)) add up: \({R}_{2}=6\text{ }\Omega\)
  • These are in parallel: \({R}_{\text{eq}}=\frac{{R}_{1}{R}_{2}}{{R}_{1}+{R}_{2}}=\frac{(3)(6)}{3+6}=2\text{ }\Omega \mathrm{.}\)

Thus, the equivalent resistance is \(2\text{ }\Omega\).

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