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Anonymous asked in Science & MathematicsPhysics · 2 months ago

Question about B-Fields?

A single current carrying circular loop of wire (R = 5 cm) is laying flat on a desk. A second, larger current carrying loop (R = 8 cm) is concentric with the first. Determine the magnitude of the net B-field at the center point if both loops carry 2 A of current, but in opposite directions?

7.5μo

10μo

15μo

2.5μo

Do I find the B field of each of the loops and subtract them from each other...? I'm not sure how that would work in terms of the current being opposite, though. Any input would be GREATLY appreciated!!!

1 Answer

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  • 2 months ago

    By B = µoi/2r

    =>B(small) = µoi/2r(small)------------------(i)

    & B(big) = µoi/2r(big) ---------------------(ii)

    Since direction of i is in opposite direction:

    =>B(net) = B(small) - B(big)

    =>B(net) = µoi/2 [ 1/r(small) - 1/r(big)]

    =>B(net) = (µo x 2)/2 x [1/(5 x 10^-2) - 1/(8 x 10^-2)]

    =>B(net) = µo x [7.5]

    =>B(net) = 7.5µo

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