Question

A wire of lenth 2mm and radius 0.2mm has a resistance of 300 ohm's

Answer 1

what is the main question

Answer 2

Given,

Resistance = 300 Ohm

Length of the wire = 2mm

$lenght(in \: m) = 2 \times {10}^{ - 3m}$

Radius = 0.2mm

$radius(in \: m) = 2 \times {10}^{ - 4} m$

$cross - section \: area = π {r}^{2}$

$= > 3.14 \times 2 \times {10}^{ - 4} \times 2 \times {10}^{ - 4}$

$= > 3.14 \times 4 \times {10}^{ - 8} {m}^{2}$

We know that,

$R = p \times \frac{l}{a}$

$= > p = R \times \frac{a}{l}$

$= > p = 300 \times \frac{3.14 \times 4 \times {10}^{ - 8} }{2 \times {10}^{ - 3} }$

$= > p = 3.14 \times 2 \times {10}^{ - 5}$

$= > p = 6.28 \times {10}^{ - 5}$

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