$A$ long copper tube of inner radius $R$ carries a current $i$. The magnetic field $B$ inside the tube is

The relative permeability in a core of a solenoid is $400$. The windings of a solenoid are insulated from the core and carry a current of $2 \ A$. If the number of turns is $1000$ per meter,then the magnetic intensity inside the core of the solenoid is . . . . . . $\frac{A}{m}$.

There are $50$ turns of a wire in every $1$ $cm$ length of a long solenoid. If $4$ $A$ current is flowing in the solenoid,the approximate value of the magnetic field along its axis at an internal point and at one end will be respectively:

The magnetic field at the centre of a long solenoid having $400$ turns per unit length and carrying a current $i$ is $6.24 \times 10^{-2} \,T$. The magnetic field at the centre of another long solenoid having $200$ turns per unit length and carrying a current $\frac{i}{2}$ is

What is the magnetic field at point $P$ located at a distance of $\frac{3R}{2}$ from the center of the cylindrical conductor with inner radius $R$ and outer radius $2R$ carrying a current $i$?

Current is flowing through a conducting hollow pipe whose cross-section is shown in the figure. The value of magnetic induction will be zero at: