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Question

Two long, straight wires cross each other at right angles, as shown in Figure P19.53.

Figure P19.53
http://www.webassign.net/sf5/p19_49.gif

(a) Find the direction and magnitude of the magnetic field at point P, which is in the same plane as the two wires.

(b) Find the magnetic field at a point 29.5 cm above the point of intersection (29.5 cm out of the page, toward you).

Answer 1

MKS
for the 3 A wire

B is into the paper

B=-μI/(2πr)=-μ3/(2π*.3)=-4πE-7*3/(2π*.3)=-2 μT

for the 5 amp wire, B is out of the paper

similar calculations yield B=+2.5μT

the Resultant field is -2+2.5=0.5μT

the distance to the wire from the 3 amp is sqrt(.3^2+(.295)^2)=0.421
from the 5 amp wire we have 0.497

field 1=-1.43E-6
field 2=2.01E-6
total field =0.58E-6 T