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A wire of a certain material is stretched slowly by ten per cent. Its new resistance and specific resistance become respectively:

1. 1.2 times, 1.3 times
2. 1.21 times, same
3. both remain the same
4. 1.1 times, 1.1 times

Correct answer: 1.21 times, same

Solution

When a wire is stretched, its length increases and its cross-sectional area decreases, leading to an increase in resistance. The resistance becomes proportional to the square of the length change, so it increases by 1.21 times. However, the specific resistance (resistivity) is a material property and remains unchanged.

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