Magnetic Effects of Current and Magnetism

The magnetic field at the centre of a circular loop of radius R carrying a current I is:

For a circular loop of radius R carrying current I, the ratio of the magnetic field at a point on its axis at distance R from the centre to the field at the centre is:

A wire bent into a semicircular arc of radius R carries a current I. The magnetic field at the centre of the arc due to the arc is:

A square loop of side a carries a current I. The magnetic field at its centre is:

According to the Biot–Savart law, the magnetic field due to a small current element at a point lying on the line of the element (along its own direction) is:

A straight wire of length 2d carries a current I. The magnetic field at a point at perpendicular distance d from the midpoint of the wire is:

A long vertical wire carries a current flowing upwards. At a point due east of the wire, the magnetic field due to the wire points:

Two concentric coplanar circular loops of radii R and 2R carry equal currents I in the same sense. The magnetic field at their common centre is:

A wire carrying current I is first bent into a circular loop of one turn and then into a circular coil of two turns (same wire length, same current). The ratio of the field at the centre in the second case to that in the first is:

A very long wire carrying current I is bent into a hairpin shape: two long straight parallel parts joined by a semicircle of radius R. The magnetic field at the centre of the semicircle is:

One tesla is equal to:

For a circular current loop of radius R, find the ratio of the magnetic field at its centre to the field at a point on its axis at a distance √3 R from the centre.