$A$ long straight wire of circular cross-section of radius $a$ is carrying a steady current. The current is distributed uniformly across the cross-section of the wire. The ratio of the magnetic fields at points $0.5a$ and $1.5a$ from the centre of the wire is

Write the equation for the magnetic field due to a circular current-carrying loop at a point on the axis of the loop. Give its special cases.

$A$ long straight wire along the $z$-axis carries a current $I$ in the negative $z$-direction. The magnetic vector field $\vec{B}$ at a point having coordinates $(x, y)$ in the $z = 0$ plane is

$A$ tightly wound $100$ turns coil of radius $10 \,cm$ carries a current of $7 \,A$. The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as $4 \pi \times 10^{-7} \,SI$ units):

Two parallel wires of equal lengths are separated by a distance of $3 \text{ m}$ from each other. The currents flowing through the first and second wire are $3 \text{ A}$ and $4.5 \text{ A}$ respectively in opposite directions. The resultant magnetic field at the midpoint of both the wires is ($\mu_0$ = permeability of free space).

If the unit of magnetic flux is in weber,then the unit of magnetic field is . . . . . . .