Question

Three infinitely long thin conductors are joined at the origin of coordinates and lie along the x-, y- and z-axes. A current i flowing along the conductor lying along the x-axis divides equally into the other two at the origin. The magnetic field at the point (0, -a, 0) has magnitude

(a) μ₀i/4πa

(b) 3μ₀i/4√2πa

(c) √5μ₀i/8πa

(d) √3μ₀i/2πa

Answer 1

Correct Answer is: (c) √5μ₀i/8πa

Let P be the point (0, -a, 0), with OP = a.

The field at P due to the current i along the x-axis is μ₀i/4πa Vector k and that due to the current i/2 along the z-axis is μ₀i/8πa Vector i.

The resultant field at P is μ₀i/4πa √(1² + (1/2)²).