Question

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loads/Practice%20Final.pdf 4/6 Problem #4. A bicycle innertube, with average radius R and tube danneter "a", is wound with 18 equally-spaced turns of Wire A. (Figure on left) A Fits Inside Wire B Ib A) Use Ampere's Law to prove that if the current through wire A is I, then the magnetic field inside of the innertube is QMo/R) Ignore the figure on the right for these first two parts dl B) Find the self-inductance L of wire A (recall ε,--L- 4 ). Again, ignore wire B C) Now the the innertube is inserted into the bicycle wheel, which has the same average radius R but has a tube diameter of"b". This outer wheel is wound with 9 equally-spaced turns of Wire B. (Figure on right) If the same current I is run around the outer wheel, in the same direction, find the B-field at the (joint) center of the toroids (in the middle of the innertube).

Answer 1

TT R Tt R (MR) (ITA

In second question flux area can change when u see for centre i.e pi (radius)^2.