Question

A 4.0m long wire has diameter of 0.30 mm. If its resistance is 30 ohm, find its resistivity & conductivity​

Answer 1

Answer:

refer to the attachment

Answer 2

Dear Student,

★Answer :

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☛ Formula :

R = p × l / a

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☛ Given :

⇒ l = 4 m  

l = 4 m  

⇒ d = 0.3 mm  

r = d / 2  

r = 0.3 mm / 2  

= > r = 0.15 mm  

r = 0.15 mm × 10⁻³ m  

⇒ R = 30 ohms

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☛ To Find :  

Resistivity ( p ) = ?

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☛ Explanation :  

∴ R = p × l / a  

⇒30 = p × 4 / 0.15 × 10⁻³  

⇒30 = p × 4 × 10³ × 100 / 15  

⇒ 30 × 15 = p × 4 × 10⁵  

⇒ p = 450  / ( 4 × 10⁵ )  

⇒p = 112.5 × 10⁻⁵  

⇒ p = 1.125 × 10⁻⁸

 

➤ Conductivity = 1 / p  

                            = 1 / 1.125 × 10⁻⁸  

                             = 1.125 × 10⁸  

➠ANSWER :

Resistivity =  1.125 × 10⁻⁸  

Conductivity = 1.125 × 10⁸