Question

a copper wire has a resistance of 0.5ohm.another wire of the same mass as the first one is double in length of first.find the resistance of second wire

Answer 1

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

Answer 2

Explanation:

• here is your answer... the main formulae is that... R = p x l/a ..

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