A wire carrying current `I` is shaped as shown. Section `AB` is a quarter circle of radius `r`. The magnetic field is directed

Options

A. perpendicular to the plane of the paper and directed into the paper
B. at an angle `pi//4` to the plane of the paper
C. along the bisector of the angle ACB away from AB
D. along the bisector of ACB towards AB

Answer

A

Explanation

The magnetic field at C due to the straight portions of the conductor is zero because the position `(vecr)` and current elements (`idvecl`) are parallel. So the field at C is only due to the circular portion. the direction will be perpendicular to the plane of the paper and directed into the paper according toright hand palm rule.