Question

The resistivity of a metal wire is 10 x 10 −8 Ω m at 20°C. Find the resistance of the same wire of 2 meter length and 0.3 mm thickness.

Answer 1

Answer:

Explanation:

Given, Resistivity (ρ) = 10 x 10^-8 Ω m, Length ( l ) = 2 m, Diameter = 0.3 mm

Resistance (R) =?

Now, Radius of wire = Diameter / 2 = 0.3 mm / 2 = 0.15 mm = 1.5 x 10^−5 m

Now, area of cross section of wire = π r^2

Or, A = 3.14 x (1.5 x 10^−5)^2

Or, A = 70.65 x 10^−10 m^2

we know that

R = ρ l/A

then you got the value of

R = 0.28×10^2=28

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