Question

A copper conductor of circular cross section 2mm in diameter is 5m long. Calculate the resistance at 20C if the resistivity of the copper is 1.72 x 10-8 ohm-m.

A. 27.37 m-ohm

B. 2.737 m-ohm

C. 273.7 m-ohm

D. 0.2737 m-ohm

Answer 1

Answer:

Explanation:

iven :   R=2Ω            l=1 m            d=0.4 mm =0.0004 m

Cross section area of wire       A=

4

πd

2

​

=

4

π×(0.0004)

2

​

=1.256×10

−7

 m

2

 

Resistivity of the material       ρ=

l

RA

∴   ρ=

1

2×1.256×10

−7

=2.514×10

−7

  Ωm