Question

Calculate the resistance of a 100 metre roll of 2.5mm2

copper wire if the resistivity of

copper at 20o

C is 1.72 x 10-8 Ω metre.​

Answer 1

Hey Pretty Stranger!

Correct Question :

Calculate the total DC resistance of a 100 metre roll of 2.5 mm² copper wire if the resistivity of copper at 20°C is 1.72 x 10⁻⁸ Ω metre.

Here, we're given with :

• Resistivity of copper at 20°C is 1.72 × 10⁻⁸ m

• Length = 100 m

• Cross sectional area = 2.5 mm²

It'd give the area as 2.5 × 10⁻⁶ m²

★ R = ρ × L/A Ω

$\sf \longrightarrow R= \: \dfrac{(1.72 \times {10}^{ - 8}) \times 100}{2.5 \times {10}^{ - 6} }$

$\sf \longrightarrow R= 0.688 \: \:$ Ω

Answer 2

Given : A 100 metre roll of 2.5mm² copper wire if the resistivity of copper at 20°C is 1.72×10⁻⁸ ohms metre

To Find :  total DC resistance

Solution:

R = ρ L/A

R = ?

ρ  =  1.72×10⁻⁸ ohms metre

L = 100 m

A =  2.5mm²  = 2.5 * 10⁺⁶ m²

R = 1.72×10⁻⁸  * 100 / 2.5 * 10⁺⁶

=> R = 1.72/2.5

=> R = 0.688

Hence Resistance is 0.688  Ohms

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