Consider a co-axial cable which consists of an inner wire of radius \(a\) surrounded by an outer shell of inner and outer radii \(b\) and \(c\) respectively. The inner wire carries a current \(I\) and outer shell carries an equal and opposite current. The magnetic field at a distance \(x\) from the axis where \(b<x<c\) is

\((a)\) \(\frac{\mu_{0} I(c^2 - b^2)}{2 \pi x(c^2 - a^2)}\)

\((b)\) \(\frac{\mu_{0} I(c^2 - x^2)}{2 \pi x(c^2 - a^2)}\)

\((c)\) \(\frac{\mu_{0} I(c^2 - x^2)}{2 \pi x(c^2 - b^2)}\)

\((d)\) \(0\)

## Comments

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TopNewestThis question is based on the application of Ampere's circuital law. Give it a try at least. :) – Pranav Arora · 4 years ago

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– Advitiya Brijesh · 4 years ago

thnx buddy bt i had already done it... it was the question that i felt was good to be posted because i got stuck in this particular question!!!!Log in to reply

– Advitiya Brijesh · 4 years ago

with your help... :)Log in to reply

hey... Is your AGE = 14 ...................?? Please Reply – Vamsi Krishna Appili · 4 years ago

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the answer will be C – Farhan Masood Laskar · 4 years ago

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8.02x, huh? – Ahaan Rungta · 4 years ago

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magnetic field due to inner wire:

mu I / (2 pi x)current between b and x:

- I (x^2 - b^2) / (c^2 - b^2)magnetic field due to current between b and x:

- [mu I / (2 pi x)] [(x^2 - b^2) / (c^2 - b^2)]magnetic field at x:

[mu I / (2 pi x)] [(c^2 - x^2) / (c^2 - b^2)]which isC– Ramon Vicente Marquez · 4 years agoLog in to reply

– Pranav Arora · 4 years ago

Ah Ramon, I was waiting for Advitiya to post his attempt. You should not have given the solution. It would be a great experience for Advitiya if he solved this by himself. :)Log in to reply

– Ramon Vicente Marquez · 4 years ago

i rarely give away full solutions. usually i just give hints. i just feel like giving the solution this time.Log in to reply

– Sudheesh Srivastava · 4 years ago

hints...this doesn't even require any hint!!Log in to reply

Sorry, option b)!!! – Subhrodipto Basu Choudhury · 4 years ago

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– Ramon Vicente Marquez · 4 years ago

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I think it will be option c)!!! – Subhrodipto Basu Choudhury · 4 years ago

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– Advitiya Brijesh · 4 years ago

hmm.. :)Log in to reply