a
A wire has a radius of 0.2 mm and resistivity
2 x 103 rm what will be the lingth of this wire
to make its resistance are?
Answers
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Answer:
Given,
l=0.1m=1000mm
d=0.2mm∴radius(r)=
2
0.2
=0.1mm
R=10Ω
To find,
Resistivity(ρ)
ρ=R
l
A
where,
R= Resistance
l= Length of wire
A= Cross sectional area of wire
Cross sectional area of cylinder (A)=Πr
2
⇒A=π×(0.1)
2
⇒A=0.0314mm
2
∴ρ=10(
1000
0.0341
)
⇒ρ=0.000314Ω−mm
⇒ρ≃3.14×10
−7
Ω−m
So, the resistivity of the material is equal to 3.14×10
−7
Ω−m
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