The magnetic field inside a long solenoid is:

$A$ toroid has a core (non-ferromagnetic) of inner radius $25 \; cm$ and outer radius $26 \; cm,$ around which $3500$ turns of a wire are wound. If the current in the wire is $11 \; A$,what is the magnetic field:
$(a)$ outside the toroid,
$(b)$ inside the core of the toroid,and
$(c)$ in the empty space surrounded by the toroid?

What are the directions of the magnetic field between and outside a pair of two parallel large sheets carrying currents in the same directions,as illustrated in the figure?

$A$ long cylindrical wire of radius $R$ carries a uniform current $I$ flowing through it. The variation of magnetic field $B$ with distance $r$ from the axis of the wire is shown by:

$A$ long solenoid has $200$ turns per $cm$ and carries a current of $2.5 \ A$. The magnetic field at its centre is $(\mu_0 = 4\pi \times 10^{-7} \ \text{Wb/A} \cdot \text{m})$.

$A$ solenoid of length $0.5 \,m$ has a radius of $1 \,cm$ and is made up of $m$ number of turns. It carries a current of $5 \,A$. If the magnitude of the magnetic field inside the solenoid is $6.28 \times 10^{-3} \,T$, then the value of $m$ is: