A uniform wire of resistance 3 ohm is folded in such a way that it forms an equilateral triangle, then what is it's resistance across the ends of any two vertices?
Correct answer: C. 2/3 ohm
- A. 2 ohm
- B. 3 ohm
- C. 2/3 ohm
- D. 3/2 ohm
Explanation
Since we have a uniform wire, therefore the resistance of each side of the triangle will be equal as the length of each is also equal. Three sides mean that each side will have resistance 3 ohm/3 = 1 ohm. If the resistance is to be measured across A and B, then it is clear that two of the three sides are connected in series: R = 1 + 1 = 2 ohms. And this combination is connected in parallel with the third side: 1/R = 1/1 + 1/2 = 3/2 R = 2/3 ohm.
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About Resistance and Resistivity
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
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