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The length of a manganin wire of diamete...

The length of a manganin wire of diameter `0.07` cm is `1.75 ` m at `20^(@)C` . If the resistivity of manganin is `4.4 xx 10^(-6) Omega `- cm , then its resistance is

A

`2 Omega `

B

`3 Omega `

C

`4 Omega `

D

`4.4 Omega `

Text Solution

Verified by Experts

The correct Answer is:
A
Given , diameter , `d = 0.07 xx10^(-2)` m
and we know that , ` r = d/2 `
So , ` r = (0.07 xx10^(-2))/2 `
Length of the wire , l = 1.75 m
Resistivity , `rho = 44 xx 10^(-6) Omega - cm = 44 xx10^(-8) Omega - m `
As we know that , resistance of wire `R = (rhol)/A = (44 xx 10^(-8) xx1.75)/(pir^(2))`
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