The magnetic induction at a point $P$ which is distant $4\, cm$ from a long current carrying wire is ${10^{ - 8}}\,Tesla$. The field of induction at a distance $12\, cm $ from the same current would be

Two very thin metallic wires placed along $X$ and $Y$-axis carry equal currents as shown here. $AB$ and $CD$ are lines at $45^\circ $ with the axes with origin of axes at $O$. The magnetic field will be zero on the line

A straight conductor carrying current $i$ splits into two parts as shown in the figure. The radius of the circular loop is $R$. The total magnetic field at the centre $P$ of the loop is

An electron is revolving round a proton, producing a magnetic field of $16\, weber/m^2$ in a circular orbit of radius $1\,\mathop A\limits^o $. It’s angular velocity will be

Infinite number of straight wires each carrying current $I$ are equally placed as shown in the figure. Adjacent wires have current in opposite direction. Net magnetic field at point $P$ is

As shown in the figure, two infinitely long, identical wires are bent by $90^o$ and placed in such a way that the segments $LP$ and $QM$ are along the $x-$ axis, while segments $PS$ and $QN$ are parallel to the $y-$ axis. If $OP = OQ = 4\, cm$, and the magnitude of the magnetic field at $O$ is $10^{-4}\, T$, and the two wires carry equal current (see figure), the magnitude of the current in each wire and the direction of the magnetic field at $O$ will be $(\mu_ 0 = 4\pi \times10^{-7}\, NA^{-2})$