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Help w/ Physics problem? "A piece of copper wire has a resistance per unit length of . . ."?
A piece of copper wire has a resistance per unit length of 6.05x10^-3 ohms/m. The wire is wound into a thin, flat coil of many turns that has a radius of 0.120 m. The ends of the wire are connected to a 12.0 V battery. Find the magnetic field strength at the center of the coil.
Answer is in Teslas (T)
**I've used equations: I=V/R and B=(µ*I)/(2*r). I varied the second equation to show B=(µ*I)/(2*pi*r), but no matter how I try it I get the answer wrong. Some insight please?
Answer:
You seem to be doing the right thing, find the steady state current through the coil then use that current and the geometry to calculate the field strength. it's all in metres so field strength in S.I. units would be o.k.
but you are not using solenoid equation mu_0*n*i where n is number of turns per metre ( at the centre of a long solenoid it doesn't matter what the radius is except as that affects number of turns per unit length) . So I would estimate the diameter of the wire ( after finding conductivity of copper ) and this would give a guess for number of turns per metre.
best of luck
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