Biot-Savart Law & Circular Coils
A straight wire carrying a current of is bent into a semi-circular arc of radius as shown in the figure. The magnetic field produced by the current at the centre of the arc. is ____________

Numerical answer type. Work it out, then open the answer.
Show answer and solution
Answer: 2
- The straight parts point along lines through O, so : they give no field at O.
- Semicircle:
- So the answer is 2 (i.e. ).