Magnetic fieldn at the centre of a circular coil of radius R carrying current 'I' is B alpha (1)/(R ) and its direction is given by right - hand thumb rule. Magnetic field at the centre of a circular are subtending an angle 0 (in degree) is Ba (1)/(R ) ((theta)/(360^(@))) and its direction can be found using right hand rule. Consider two circular coils made of uniform conductors as shown in figure 3 and 4. In figure 3, points C and D are diametrically opposite to each other and in figure 4, angle PO = Q = 120^(@) . Then magnetic fields __________ .