In a current-carrying long solenoid,the magnetic field produced does not depend upon:

$A$ solenoid of length $80 \, cm$ and radius $3 \, cm$ produces a magnetic field of $B = 0.2 \, T$ when a current of $10 \, A$ is passed through it. What is the total length of the wire used in the solenoid?

$A$ solenoid has a core of a material with relative permeability of $400$. The solenoid windings are insulated from the core and carry a current of $2 \text{ A}$. If the number of turns is $1000$ per meter,then the value of magnetic intensity will be . . . . . . .

Two toroids $1$ and $2$ have total number of turns $200$ and $100$ respectively with average radii $40 \; cm$ and $20 \; cm$ respectively. If they carry the same current $i$,the ratio of the magnetic fields along the two loops is

What current must be passed through a solenoid with $20 \text{ turns/cm}$ to produce a magnetic field of $20 \text{ mT}$ (in $\text{ A}$)? (Given: $\frac{\mu_0}{4\pi} = 10^{-7} \text{ T m/A}$)

The magnetic energy stored in a long solenoid of area of cross-section $A$ in a small region of length $L$ is