An infinitely long conductor PQR is bent to form a right angle as shown. A current f flows through PQR. The magnetic field due to this current at the point M is H1. Now another infinitely long straight conductor QS is connected at Q so that the current is I/2 in QR as well as in QS. The current in PQ remains unchanged. The magnetic field at M is now H2. The ratio H1/H2 is given by
Magnetic field at any point lying on the axis of a current carrying straight conductor is zero.
Here H1 = Magnetic field at M due to current in PQ.=
H2 = Magnetic field at M due to QR
+ magnetic field at M due to QS
+ magnetic field at M due to PQ
= 0 ++=. Therefore