Question

1. A wire of length lm and radius 0.1 mm has a resistance 100 ohms , the
resistivity of the material
a) 0.0314 ohms m
b) 0.00341 ohms m
c) 0.00314 ohms m
d) 0.00413 ohms m​

Answer 1

Explanation:

PHYSICS

A wire of a length 1m and radius 0.1 nm has a resistance 100 Ω Find the resistivity of the material.

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ANSWER

Given: A wire of a length, L=1m and radius, r=0.1nm=0.1×10 −9

m has a resistance, R=100Ω

To find the resistivity of the material

Solution:

We know,

R=ρ

AL

, where ρ is the resistivity of the material, A=πr2

is the area of cross-section.

By substituting the given values,

100=ρ

π×r

21

⟹100=ρ

3.14×(0.1×10 −9 )21

⟹ρ=100×3.14×10

−20

=3.14×10 −18 Ωm