Physics 21Fall, 2004Solution to HW-1328P18Two long parallel wires 7.0 cm apart carry 16.5 Acurrents in the same direction. Determine the magnetic feldstrength at a pointP12.0 cm From one wire and 13.0 cmFrom the other.αβααπ/2 − αBB1ββπ/2 − βB2The feldBat the pointPwill be the vector sum oF thefelds From the two wires. We must fnd the components oFthe two felds so we can add them. We can use the Law oFCosines to solve For the anglesα:132=122+72−2(12)(7) cosα⇒α=81.79◦122=1322−2(13)(7) cosβ⇒β=66.01◦The magnitude oF the felds are obtained FromB=µ0I/2πR,whereR1=0.012 m For the leFt wire andR2.013 m Forthe right wire. The diagrams show how we can use geometryto fnd the components oFB1andB2:B1=µ0I2π(0.12 m)³−cos(π/2−α)ˆi+sin(2−α)ˆj´B2=µ0I2π(0.13 m)³−cos(2−β)ˆi−sin(2−β)ˆj´Subsituting the numbers, we fndB=B1+B2=(−5.04ˆi−0.64ˆj)×10−5T28P32A small loop oF wire oF radius 1.8 cm is placed at
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This note was uploaded on 08/06/2008 for the course PHYS 21 taught by Professor Hickman during the Fall '07 term at Lehigh University .