It is found that a non-zero current element is unable to produce any magnetic field at a particular point. Then the angle between the current element and the position vector of that point with respect to the current element is

$A$ single current-carrying loop of wire with current $I$ flowing in an anticlockwise direction when seen from the $+ve\;z$ direction,lying in the $xy$ plane,is shown in the figure. The plot of the $\hat{j}$ component of the magnetic field $(B_y)$ at a distance $a$ (less than the radius of the coil) on the $yz$ plane versus the $z$ coordinate looks like:

The magnetic field at the origin due to the current $I$ flowing in the wire as shown in the figure is:

$A$ thin ring of $10 \, cm$ radius carries a uniformly distributed charge. The ring rotates at a constant angular speed of $40 \pi \, rad \, s^{-1}$ about its axis,perpendicular to its plane. If the magnetic field at its centre is $3.8 \times 10^{-9} \, T$,then the charge carried by the ring is close to $\left( \mu_0 = 4 \pi \times 10^{-7} \, N/A^2 \right)$.

$A$ negative charge is moving towards the observer. What will be the direction of the magnetic field produced by it,as seen by the observer?

Two parallel conducting wires are placed at a distance of $32 \text{ cm}$. $A$ current of $8 \text{ A}$ flows through each wire in opposite directions. The magnitude of the magnetic field at the midpoint between the two wires is . . . . . . $\mu \text{T}$. (Given: $\frac{\mu_0}{4\pi} = 10^{-7} \text{ N/A}^2$)