The current is flowing along the path $abcd$ of a cube (shown to the left) 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,

A  V-shaped wire lies in the $x-y$ plane. The direction of the magnetic field at $P$ is

A coil placed in the plane of paper has a current in clockwise direction when looking from above. What will be the change in the direction of magnetic field at the centre of the coil if current is reduced to half and radius is doubled.

An electric $\mathrm{I}$ flow through an infinitely long conductor as shown in figure. Write an expression and direction for the magnetic field at point $\mathrm{P}$ .