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The resistance of a wire is 'R' ohm. If it is melted and stretched to 'n' times its original length, its new resistance will be:

1. R/n
2. n²R
3. R/n²
4. nR

Correct answer: n²R

Solution

When a wire is stretched to n times its original length, its length becomes nL and its cross-sectional area decreases by a factor of n (since volume remains constant). Resistance is proportional to the square of the length, so the new resistance becomes n²R.

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