Question

A copper wire has diameter of 0.5mm and resistitivy of 1.6X10
-8 Ωm. What will be the

length of this wire to make its resistance 10Ω? How much does the resistance change if the
diameter is double.​

Answer 1

Answer:

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Given,

diameter of copper wire = 0.5mm = 5 × 10-⁴ m

resistivity = 1.6 × 10^-8 ohm.m

resistance = 10 ohm

Length = ?

we know,

R = dL/A

where R , d , L and A are resistance , resistivity , length and cross section area.

10 = 1.6 × 10^-8 × L/(πr²)

L = 10 × 3.14 × (2.5 × 10^-4)² × 10^8/1.6

L = 10× 3.14 × 6.25/1.6

L = 122.656 m