Question

Figure shows two very long conductors PQ and RS kept parallel to each other in vacuum at a distance of 20 cm. They carry currents of 5 A and 15 A, respectively, in the same direction, as shown. Find the resultant magnetic flux density BR at a point M which lies exactly midway between PQ and RS.

Answer 1

Here I₁ = 5A, I₂ = 15A, r = 10cm = 0.1m

The magnetic flux density at the point M due to the current of 5A

inwards ⊥ to the plane of the conductor

= 10^-5 T inwards

Similarly, the magnetic field B₂ at M due the current of 15A in RS

∴ Resultant magnetic field at M is the difference of the two because they are in opposite direction.

∴ B = B₂ - B₁ = 3 X 10^-5 - 10^-5

= 2 x 10^-5 T outwards