Homework SourseTwo long parallel wires are shown in the figure below They a
Two long parallel wires are shown in the figure below. They are separated by a distance L = 20.0 cm. The bottom wire carries a current of 6.40 A in the direction shown. The current of the upper wire is directed in the opposite direction. The total magnetic field at point A is zero, and the distance d between point A and the bottom wire is 7.0 cm. What is the current in the top wire? As usual, the figure is most likely not to scale.
Solution
Here ,
L = 20 cm = 0.20 m
current in bottom wire , I1 = 6.4 A
d = 7 cm = 0.07 m
let the current in the top wire is I2
for the net magnetic field at point A to be zero
u0 * I1/(2pi * d) = u0 * I2/(2pi * (d + L))
6.4/0.07 = I2/(0.07 + 0.20)
I2 = 24.7 A
the current in the top wire is 24.7 A
