SSC JE Electrical Engineering 23 Jan 2018 Morning Paper

Question : 105 of 200

Marks: +1, -0

Find the resistivity of a material (in Ohms–cm) of wire whose resistance is 5 ohms. (Assume length of the wire is 15 m, diameter of wire is 0.15 cm)

Solution:

Given data
R = 5 Ω
l = 15 m = 1500cm
d = 0.15 cm ⇒ r = 0.075 cm
ρ = ?
As we know that

R=ρl/A

⇒ρ={R×A}/l

={5×π(0.075)^2}/1500

5.87 × 10^{–5 }

Ω - cm

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