what is the resistance if it length is tripled and its initial resistance is 15 ohm
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Answers
Mark as BRAINLIEST.
The answer is 45 ohms.
Assuming the wire is uniformly stretched to three times its original length L, then in order to maintain constant volume (which for a uniform cylinder is equal to length times cross-sectional area), the cross sectional area of the wire will also decrease by a factor of three. Since in most wire, resistance is proportional to cross-sectional area, then the resistance should increase by a factor of three. However, the stretching has also increased the length by 3x, and resistance varies directly with length. Thus the combined effect of stretching the wire to 3x its original length, while simultaneously decreasing its cross-sectional area by 3x, increases the resistance by a factor of 3 • 3 = 9, resulting in a final stretched resistance of 5Ω • 9 = 45Ω (ohms).