A semi-infinite straight conductor carries a current I P is a point at perpendicular distance a
from the conductor as shown. The field at P due to the conductor is :

A point charge q is in motion with velocity \[\overrightarrow{v}] relative to an inertial axis ‘A’. The instantaneous location of q with respect to a fixed observation point P is \[\overrightarrow{r}\] as shown. \[\overrightarrow{B}\]
the magnetic field at point P is given by :

A wire carrying current I has the shape as shown in adjoining figure. Linear parts of the wire are
very long and parallel to X-axis while semicircular portion of radius R is lying in Y-Z plane. Magnetic field at point O is :

A long straight, hollow, conductor (tube) carrying a current has two sections A and C of unequal cross sections joined by a conical section B. 1, 2 and 3 are points on a line parallel to the axis of the conductor. The magnetic fields at 1, 2 and 3 have magnitudes B1, B2 and B3. Then :

Two parallel long wires carry currents i1 and i2 with i1 > i2. When the currents are in the same
direction, the magnetic field midway between the wires is 10μT. When the direction of i2 is reversed, it becomes 40μT. the ratio i1/i2 is :

The magnetic field at the centre of an equilateral triangular loop of side 2L and carrying a current i is :

Two wires AO and OC carry equal currents i as shown in figure. One end of both the wire extends to infinity. Angle AOC is α. The magnitude of magnetic field at a point P on the bisector of these two wires at a distance r from point O is :

In the above figure magnetic field at point C will be:

A wire carrying a current i is placed in a uniform magnetic field in the form of the curve
y =a sin (πx/L), 0 ≤ x ≤ 2L. The force acting on the wire is :

Two thick wires and two thin wires, all of the same materials and same length form a square in
the three different ways P, Q and R as shown in fig with current connection shown, the magnetic field at the centre of the square is zero in cases: