Question

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A given wire of resistance 1 ohm is stretched to double its length. What will be its new resistance?

Plzz do it step wise!!

Answer 1

Resistance = Resistivity * Length / Area
The Resistivity will remain constant.

Now, Volume = Length * Area of cross section

So,Volume remains constant
l * A = 2l * A'
So, new area will be A' = A/2
So,
New resistance = Resistivity * 2l / A/2 = Resistivity * l/A * 4 = 4 * Original resistance

So, the resistance will increase 4 times

Answer 2

it's new resistance is given by

R= n^2r

R=4r

hence it's resistance increase four times than original value.