1.

The length of a given cylindrical wire is increased by `100%`. Due to the consequent decrease in diameter the change in the resistance of the wire will beA. `300%`B. `200%`C. `100%`D. `50%`

Answer» Correct Answer - A
(a) If suppose initinal length `l_(1) = 100` then
`l_(2) = 100 + 100 = 200`
`(R_(1))/(R_(2)) = ((l_(1))/(l_(2)))^(2) = ((100)/(200))^(2) implies R_(2) = 4 R_(1)`
`(Delta R)/(R ) xx 100 = (R_(2) - R_(2))/(R_(1)) xx (4 R_(1) - R_(1))/(R_(1)) xx 100 = 300%`


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