q9_sol_c28

# q9_sol_c28 - Quiz 9 Phys. 2306 F09 You may use your text...

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Quiz 9 Phys. 2306 F09 You may use your text book, notes, and a calculator. Three inﬁnitely long wires run from -∞ ≤ z ≤ ∞ and carry currents of mag- nitude I. The current in wire 1 that passes through the point (x,y) = (0,a) ﬂows in the +z direction, the current in the wire 2 that passes through the point (x,y) = (0,-a) ﬂows in the -z direction, and the current in wire 3 that passes through the point (x,y) = (b,0) ﬂows in the -z direction. 1) What is the direction of the magnetic ﬁeld at wire 3? a) +x b) -x c) +y d) -y e) none of these Choose the x,y,z axes i , j , k in the following directions: right, up, out of pa- per. Wires 1 and 2 are both a distance d = a 2 + b 2 from wire 3. Thus the ﬁelds at wire 3 have equal magnitudes, B = μ 0 I 2 πd . However, they point in diﬀerent directions. The directions of the ﬁeld lines from each wire are concentric circles about wires 1 and 2. So draw a circle of radius d with centers at wire 1 and 2 and where the circles intersect wire 3 draw the tangents in the correct sense. For wire 1, B

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## This note was uploaded on 12/24/2011 for the course PHYS 2306 taught by Professor Ykim during the Fall '06 term at Virginia Tech.

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q9_sol_c28 - Quiz 9 Phys. 2306 F09 You may use your text...

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