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I have a homework problem my teacher gave and warned us it was "Very difficult". ive tried drawing out the forces and i think i have made some headway but the vector-nature of magnetism confuses me... For example, i see in some solutions the forces along the y cancel and i dont know how that conclusion is made (i might be using RHR wrong).

Anyway here is my question: (OR SEE ATTACHMENT)

Three current carrying wires are configured into a PENDULUM. With the top vertex being stationary and carrying current I2= 2A (OUT OF THE PAGE). Off either side of the vertex are wires having I1= sqrt((mg*pi)/micr) a length of 1m, mass m and the string length is 1/6 m.

Find the ANGLE that the wires come to equilibrium.

Here is my work:

** Forces on a Pendulum **

Fy= Tension (along Y) = Gravitational force (mg)

Fx= Tension (along x) = Magnetic Force (BIL sin (theta))

therefore: F= mg (sin/cos theta) and since F= BIL sin (theta)

BIL sin (theta)= mg (sin/cos theta) [sin theta cancels leaving]

***theta= cos^-1 (mg/BIL)***

B can be substituted with (micro0*I/ 2*pi*r) but as long as i cant figure out B i cant solve the problem. HELP!

Thanks for your time,

Mike

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# Magnetism and Current Carrying wires (?)

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