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What is the resistance of

a. 2.0m-long gold wire that is 0.20mmin diameter?

b. A 10cmlong piece of carbon with a 1.0mm×1.0mmsquare cross-section?

Short Answer

Expert verified

a. The resistance of a 2.0mlong gold wire that is 0.20mmin diameter is1.53Ω.

b. The resistance of a long piece of carbon with a 1.0mm×1.0mmsquare cross-section is3.5Ω.

Step by step solution

01

Given Information (Part a) 

Gold wire length=2.0m

Diameter=0.20mm

02

Explanation (Part a)

The resistance in the first case, since the cross-section area is a circle, will be given by

R=ÒÏLA

Modify the expression,

=ÒÏ4LÏ€D2

Substitute the values,

R=2.4×10-8Ωm×4×2mπ×0.0002mm2

R=1.53Ω

03

Final Answer (Part a) 

Hence, the resistance of a 2.0mlong gold wire that is 0.20mmin diameter is 1.53Ω.

04

Given Information (Part a) 

Carbon Cross-section dimension=1.0mm×1.0mm

05

Explanation (Part b)

The resistance in the second case, since the cross-section area is a square, will be given by

R=ÒÏLA

=ÒÏLa2

Substitute the values,

R=3.5×10-5Ωm×20.001mm2

=3.5Ω

06

Final Answer (Part a) 

Hence, the resistance of a long piece of carbon with a 1.0mm×1.0mmis 3.5Ω.

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