Question

A wire of resstance 20 ohm is pulled till its length becomes double find new resistance

Answer 1

Given resistance = R1 = 20 ohm

Let length of the wire = L

Therefore, new length of the wire = 2L

Since, when the length is doubled, cross sectional area of the wire becomes half.

Therefore, new resistance = R = 2L/ (A/2) =4L/A

R = 4 x 20 (since, L/A = resistance)

R = 80 ohm.

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Answer 2

If the lenth of the wire is doubled then the resistance get halfed so

Given20ohm resistance of the wire

20/2=10ohm

The resistance of the wire when its lenth is doubled is 10ohm

Here we go