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The resistance of a wire is 20 ohm. It i...

The resistance of a wire is `20 ohm`. It is so stretched that the length becomes three times, then the new resistance of the wire will be

A

6.67 ohm

B

60.0 ohm

C

120 ohm

D

180.0 ohm

Text Solution

Verified by Experts

The correct Answer is:
D
`R prop L/A`
`L. = 3L` and `A. = A/3`
`therefore R_(2) = (3R_(1))/(1//3) rArr R_(2) = 9R_(1) = 9 xx 20`
`= 180 Omega`
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