Question

a copper wire has a ressistance of 0.5 ohm . another copper wire has the same mass but is twice in length than the first wire . find the ressistance of the second wire

Answer 1

Answer:

Both the wires have same mass and also they are of the same material. So, their density is same and hence their volume will also be same.

Let ρ be the resistivity of the material of the wire.

First wire:

Length = L

Area of cross-section = A

Resistance, R = ρL/A

Second wire:

Length = 2L

Area of cross-section = A/

Since, volume of the wires are same.

Volume = AL = A/(2L)

=> A/ = A/2

So, the resistance of the second wire is,

R/ = ρ(2L)/(A/2) = 4R = 4 × 0.5 =1. 0 Ω