Magnetic Field and Biot-Savart's Law

A small current element of length $\mathrm{d}l$ and carrying current $i$ is placed at $(1,1,0)$ and is carrying current in $+z$ direction. If the magnetic field at origin be ${\overrightarrow{B}}_1$ and at point $(2,2,0)$ be ${\overrightarrow{B}}_2$ then 

A particle is moving with velocity $\overrightarrow{v}=\hat{\mathrm{i}}+3\hat{\mathrm{j}}$ and it produces an electric field at a point given by, $\overrightarrow{E}=2\hat{\mathrm{k}}$. It will produce magnetic field at that point equal to (all quantities are in SI units)

Two observers moving with different velocities see that a point charge produces same magnetic field at the same point $A$. Their relative velocity must be parallel to $\overrightarrow{r}$, where $\overrightarrow{r}$ is the position vector of point $A$ with respect to the point charge. This statement is,

An electron is moving in a circular orbit of radius $r$ with a linear velocity $v$ in a hydrogen atom. The magnetic induction produced at the nucleus will be,

The value of intensity of magnetic field due to a current-carrying coil is maximum

The value of intensity of magnetic field at any point due to a current-carrying element depends