Ampère's law in free space may be written as ∮ ? . ?? = ???
a) Write the equation in words, giving the meaning of eachparameter.
b) Starting with the equation above obtain an expression for thelaw in differential form.
c) A long wire P carries a current ?. Use the law to show thatthe magnetic field at a radial distance r from the wire is ? = ???/ 2?? [3] [4] [4] Page 4 of 4 A second long wire Qis placed parallel to wire P, with the two wires separated by aperpendicular distance ?. The second wire also carries a current ?but in the opposite direction to the current in wire P.
d) Draw a diagram to illustrate the wires and the directions ofthe currents.
e) Show on the diagram the directions of the forces that thewires experience. Explain clearly the reason for thesedirections.
f) Show that the force per unit length on the wires is ??? ^2 /2??
g) Power lines separated by a distance of 2.0 m carry a currentof 180 A. Determine the force per unit length experienced by eachwire.
