A long thin walled pipe of radius R carries current I along its length.The current density is uniform over circumference of pipe.The magnetic field at the centre of pipe due to quarter portion of pipe?-Please answer and explain.....

total current through circumfrence  = I

 current through unit segment of circumfrenece = I/2piR                   (current dencity)

length of quater of segment = 2piR/4 = piR/2

 current through quater segment (piR/2)= (I/2piR)(piR/2)

                                                        =I/4

now we have , B.dl = u_oI(current threading)

                    B(2PiR) = u_o(I/4)

                    B = u_oI/8piR