Question

A wire of resistance 10 ohm is elongated by 10%. The resistance of the elongated wire is

Answer 1

#.A wire of resistance of 10 ohms is elongated by 10%. The resistance of the elongated wire is?

Ans:
Let resistance of a conductor = ρL/A

Where ρ is the resistivity of the material, L is the length and A is the cross sectional area.

Let's assume the wire is cylindrical.

Volume of a cylinder = V = πr^2 x h

Where r is the radius and h is the height.

Here, A = πr^2 and h = L

So, V = AL

When you are stretching the volume will remain the same.

So V = A'L' = A'x(1.1)L (stretching by 10%)

Thus A' = V/(1.1L) = 0.909A

So new resistance = ρL'/A' = ρx1.1L/(0.909xA) = 1.21R = 12.1Ω