Question

A copper wire has a resistance of 0.5 ohm. Another copper wire of the same mass and the first one is double the length of the first. Find the resistance 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

Explanation:

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Answer 2

Answer:

R1=0.5 ohm,  L1=x

And, R∝L

Therefore, L2=2x

L∝R

=>2L∝2R

=>0.5X2= 1 ohm

Explanation:

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