Question 26

If a copper wire is stretched to increase its length by 20%. The percentage increase in resistance of the wire is _____%.

Name: If a copper wire is stretched to increase its length by 20%. The percentage increase in resistance of the wire is _____%.
Uploaded: 2026-05-13T11:46:58.752017+05:30
Duration: 1 min 22 s
Description: If a copper wire is stretched to increase its length by 20%. The percentage increase in resistance of the wire is _____%.

Correct Answer: 44

Solution

$$R = \rho \frac{L}{A}$$

$$V = A \cdot L$$

$$R = \rho \frac{L^2}{V}$$

A 20% increase in length means the new length is $$L' = 1.2L$$.

$$\frac{R'}{R} = \left(\frac{L'}{L}\right)^2$$

$$\frac{R'}{R} = (1.2)^2 = 1.44$$

$$\% \text{ increase} = (1.44 - 1) \times 100 = 44\%$$

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If a copper wire is stretched to increase its length by 20%. The percentage increase in resistance of the wire is _____%.

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