Magnetic Effects Of Current Question 437
Question: Three infinitely long wires are placed equally apart on the circumference of a circle of radius a, perpendicular to its plane. Two of the wires carry current I each, in the same direction, while the third carries current 2I along the direction oppo- site to the other two. The magnitude of the magnetic indution $ \overset{\to }{\mathop{B}}, $ at a distance r from the centre of the circle, for r > a, is
Options:
A) 0
B) $ \frac{2{\mu_{0}}}{\pi }\frac{I}{r} $
C) $ -\frac{2{\mu_{0}}}{\pi }\frac{I}{r} $
D) $ \frac{2{\mu_{0}}}{\pi }\frac{Ia}{r^{2}} $
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Answer:
Correct Answer: A
Solution:
[a] From ampere circuital law $ \oint{B.dl={\mu_{0}}i} $ Where, i= Net current passing through the loop Now $ i=I+I-2I=0 $
$ \therefore ,B.2\pi r=0\Rightarrow B=0 $
BETA
