Question

a long straight telephone cable content six words each carrying a current of 0.5 A the distance between the wires is negligible .what is the magnitude of magnetic field at a distance 10 centimetre from the cable (I) if the currents in all the six wires are in same direction and (ii) if four wires carrying current in one direction and the other two in opposite direction

Answer 1

Dear Student,

Please find below the solution to the asked query:

According to the Ampere's Circutal Law, the equation for the magnetic field due to current carrying wires is,

(i)

If all the currents are moving in the same direction.

Bnet=μ0Inet2πR=10−7×2×6×0.50.1⇒Bnet=6×10−6 T

(ii)

If the currents in two wires are moving in opposite direction to the currents in other wires, then

Bnet=μ0Inet2πR=10−7×2×2×0.50.1⇒Bnet=2×10−6 T

Hope this information will clear your doubts about the topic.