Straight Wire (7, 1)
The magnetic field calculation differs depending upon whether the point is inside or outside the wire.
Equation:
∝ 0 ⋅ ∝ r ⋅ I B =
2 ⋅ π ⋅ r
Example:
Given: ∝r=1, rw= 0.25_cm, r=0.2_cm, I=25_A.
Solution: B= 0.0016_T.
Force between Wires (7, 2)
The force between wires is positive for an attractive force (for currents having the same sign).
Equation:
∝ 0 ⋅ ∝ r ⋅ L ⋅ Ib ⋅ Ia
Fba =
2 ⋅ π ⋅ d
Example:
Given: Ia=10_A, Ib=20_A, ∝r=1, L=50_cm, d=1_cm.
Solution: