A current-carrying loop consists of 3 identical quarter circles of radius R, lying in the positive quadrants of the x-y, y-z, and z-x planes with their centers at the origin, joined together. Find the direction and magnitude of B at the origin.

Hint: Use the formula of the magnetic field due to a circular loop.
Step 1: For the current-carrying loop quarter circle of radius R, lying in the positive quadrants of the x-y plane:
B1=μ04πI(π/2)Rk^=μ04I2Rk^
For the current-carrying loop quarter circle of radius R, lying in the positive quadrants of the y-z plane:
B2=μ04I2Ri^
For the current-carrying loop quarter circle of radius R, lying in the positive quadrants of the z-x plane:
B3=μ04I2Rj^
Step 2: The net magnetic field is equal to the vector sum of the magnetic field due to each quarter and given by
B=14π(i^+j^+k^)μ0I2R