When current is passed through a circular wire prepared from a long conducting wire, the magnetic field produced at its centre is B. Now a loop having two turns is prepared from the same wire and the same current is passed through it. The magnetic field at its centre will be ..............

Two thin metallic wires lie on $X$ and $Y$-axes and both carry the same current as shown in the figure below. $AB$ and $CD$ are the two lines making angles $45°$ with the axes and the origin of axes is $O$. The magnetic field will be zero

A square loop is made from a uniform wire as shown in the figure. If a battery is connected between the points $A \& C,$ then the magnitude of the magnetic field at the center of the square is

The current in flowing along the path $ABCD$ of a cube (shown in the left figure) produces a magnetic field at the centre of cube of magnitude $B$. Dashed line depicts the non-conducting part of the cube.

Consider a cubical shape shown to the right which is identical in size and shape to the left. If the same current now flows in along the path $DAEFGCD$, then the magnitude of magnetic field at the centre will be

In the given figure, the magnetic field at $\text{'}O\text{'}$.