A current I is flowing in a conductor shaped as shown in figure. The radius of the curved part is r and length of straight portion is very large. Find the magnetic field induction at the centre O.

A current i is flowing in a conductor PQRST shaped as shown in the figure. The radius of curved part QRS is r and length of straight portions PQ and ST is very large. The magnetic field at the centre O of the curved part is -

A current I flows along a thin wire shaped as shown in figure. The radius of the curved part of the wire is r. The field at the centre O of the coil is:

A current I is flowing through the loop , as shown in the figure . The magnetic field at centre O is

A current l flows through a closed loop as shown in figure .The magnetic field at the centre O is

If a long horizontal conductor is bent as shown in figure and a current I is passed in it, find the magnitude and direction of magnetic field induction at the centre of circular part.