(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

a coaxial cable carries current as follows: (see attachment)

at point P, 0.3 meters from the central axis, the magnetic field is 0.005 Teslas, what is current, I?

2. Relevant equations

magnetic field solenoid, B = mu_0(n)I where mu_) is constant = 4pi*10^-7, n is number of coils/turns, I is current

magnetic field, Biot-Savart, B = mu_0/4pi([integral(IdL/r^2)]) where dL is change in length, r is radius

3. The attempt at a solution

should i assume that the coaxial cable is a solenoid? i am doubtful because the equation does not involve radius, which i am supposed to involve to solve for I.

i'm sure i'm supposed to use the biot-savart equation, do i assum dL remains constant? how do the involve the two different currents going in opposite directions?

my initial plan was to set up three biot-savart equations, one using the center conductor, the other using the outer conductor. i would then equate the sum of them two, to the third which would use r = 0.3 meters.

i think it may work except, i do not know how to differentiate the different radius of the center/outer conductors.

help appreciated

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# Homework Help: Coaxial cable and magnetic field

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