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Electric Current> A tightly coiled spring having 75 coils,e...

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A tightly coiled spring having 75 coils,each 3.5 cm in diameter is made of insulated metal wire 3.25 mm in diameter. An ohm meter connected across its opposite ends reads 1.74ohm . what is the reseptivity of metal ?

Aarmin Thapa Magar , 6 Years ago

Grade 12

1 Answers

Md Mushahid

let us consider given 75 coils

diameter of coiled spring d_c = 3.50cm = $3.5\times 10^{-2}$ m

diameter of insulated metal wire d_m = 3.25mm = $3.25\times 10^{-3}$ m

$R =1.74\Omega$

$\rho = \frac{R\times A}{L}$

First we need to find the value of L,A

$L=75\times \pi \times 3.50\times 10^{-2}$

L =8247m

$A = \pi \times r ^{2} = \frac{\pi }{4}\times d ^{2}$

$A = \frac{3.142 }{4}\times\left ( 3.25\times 10^{-3} \right )^{2}$

$A = 8.296\times10 ^{-6} m$

$\rho = \frac{R\times A}{L}$

$\rho = \frac{1.74\times 8.296\times 10^{-6}}{8.247}$

$\rho = 1.7540\times 10^{-6} \Omega m$

Last Activity: 6 Years ago

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