The figure shows the cross section of two long coaxial tubes carrying equal current `I` in opposites directions. If `B_1` and `B_2` are magnetic fields at point 1 and 2 as shown in figure then

The figure shows the cross-section of a long cylindrical conductor of radius a carrying a uniformly distributed current i. The magnetic field due to current at P is :

The figure shows the cross-section of a long cylindrical conductor of radius a carrying a uniformly distributed current i. The magnetic field due to current at P is :

Figure shows two long, straight wires carrying electric currents in opposite directions. The separation between the wires is 5.0 cm. Find the magnetic field at a point P midway between the wires.

Figure shows two parallel wires separated by a distance of 4.0 cm and carrying equal currents of 10A along opposite directions. Find the magnitude of the magnetic field B at the points A_1, A_2, A_3 and A_4.

In a coaxial, straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero.

In a coaxial, straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero.

In a coaxial, straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero.

Two similar coaxial coils, separated by some distance, carry the same current I but in opposite directions. The magnitude of the magnetic field B at a point on the axis at the mid point of the line joining the centre is :