a long straight wire of radius a carries steady current I .The current is uniformly distributed across its cross section, The ratio of the magnetic field at a/2 and 2a from axis is
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a long straight wire of radius a carries steady current I .The current is uniformly distributed across its cross section, The ratio of the magnetic field at a/2 and 2a from axis is
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A long straight wire of radius ‘a’ carries steady current I. also question said “ current is uniformly distributed.”
now, magnetic field due to straight long wire at perpendicular distance from its axis is found by Ampere circuital law,
here, is current enclosed by amperian path.
case 1 : magnetic field at a/2 :
here, =
so, B . dl =
or, B. 2π(a/2) = I/4
or, B = ....(1)
case 2 : magnetic fiend at 2a :
here, because total current flows through wire is I.
so, B'. dl' =
or, B'. 2π(2a) =
or, B' = ... (2)
from equations (1) and (2),
Answer: 1
Explanation:
Please find the explanation in the attachment. ..Hope this helps. . .