An arc of a circle of raduis `R` subtends an angle `(pi)/2` at the centre. It carriers a current `i`. The magnetic field at the centre will be

A current i ampere flows in a circular arc of wire whose radius is R , which subtend an angle 3pi//2 radian at its centre. The magnetic induction B at the centre is

A current i ampere flows in a circular arc of wire whose radius is R , which subtend an angle 3pi//2 radian at its centre. The magnetic induction B at the centre is

A current i ampere flows in a circular arc of wire whose radius is R , which subtend an angle 3pi//2 radian at its centre. The magnetic induction B at the centre is

A current i ampere flows in a circular arc of wire whose radius is R , which subtend an angle 3pi//2 radian at its centre. The magnetic induction B at the centre is

A wire bent in the form of a sector of radius r subtending an angle theta^(@) at centre as shown in figure is carrying a current I. The magnetic field at O is :

A wire bent in the form of a sector of radius r subtending an angle theta^(@) at centre as shown in figure is carrying a current I. The magnetic field at O is :