How is the EM-Force between current wires calculated in this problem?

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SUMMARY

The discussion focuses on calculating the electromagnetic force (EM-Force) between current-carrying wires, specifically addressing Problem 105 from Tipler and Mosca. A long straight wire carrying a current of 20 A interacts with a rectangular coil carrying 5 A, with dimensions of 5 cm and 10 cm, positioned 2 cm away. The magnetic field (B) was calculated using the formula B = (μ * I) / (2 * π * r), leading to forces of F(2) = 100 * 10^-4 N and F(4) = -0.286 * 10^-4 N for the coil segments. The net force on the coil was derived from the contributions of each segment, confirming the importance of using the correct current values in the calculations.

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  • Understanding of electromagnetic theory, specifically Ampère's Law.
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  • Knowledge of force calculations using F = BIL in the context of current-carrying conductors.
  • Basic proficiency in solving physics problems involving magnetic fields and forces.
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  • Study the Biot-Savart Law for a deeper understanding of magnetic field calculations.
  • Learn about the applications of Ampère's Law in various electromagnetic scenarios.
  • Explore the concept of magnetic flux and its relation to induced electromotive force (EMF).
  • Investigate the effects of varying current and distance on the forces between parallel wires.
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[SOLVED] EM-Force between current wires

Homework Statement



Problem 105 in chapter 27 Tipler and Mosca for those playing at home...

A long straight wire carries a current of 20 A, as shown in the figure. A rectangular coil
with 2 sides parallel to the straight wire has sides 5 cm and 10 cm with the near side at a
distance 2 cm from the wire. The coil carries a current of 5 A. (a) Find the force on each
segment of the rectangular coil due to the current in the long straight wire. (b) What is the
net force on the coil?

27-105.jpg


Homework Equations



good question
i used B= (mu)*I/(2*pi*r) [sorry, i can't use latex...]
and F=BIL

The Attempt at a Solution



The answers are F(2)= 100*10^-4N, F(4)= -0.286*10^-4N

For the two sides parallel (the 10cm ones),
I found B(a)=0.0002T
B(b)=0.0000571T
The other two wouldn't be effected cos they're perpendicular

F=BIL
F(a)=4*10^-4N
F(b)=1.14*10^-4N
...which are wrong

Is it something to do with the area and hence flux and shiznizzle?
 
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wait a minute team, you would use different current values in the two equations, because one is the field due to one wire, and the second is the force on the other wire right?? ooooooooh, of course...

bahaha, got to love how i only solved it AFTER i posted it.
 

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