Question

Find the magnetic field at point P in the figure below, where I = 15 A and R = 20 cm.

Answer 1

The magnetic field at the center of a current loop with current I and radius R is B=μoI2R

What we have here is a half-loop, therefore

B=12×μoI2R

⇒B=12×4π×10−7N/A2×15A2×20cm

⇒B≈24μT