The magnetic field inside a long solenoid is:

How can the magnetic field of a solenoid be increased for a given current?

For a long current-carrying solenoid,the magnetic field inside is $0.6 \ T$. The magnetic energy per unit volume is . . . . . . .

$A$ toroid has a core (non-ferromagnetic) of inner radius $24 \ cm$ and outer radius $26 \ cm$ around which $2000$ turns of a wire are wound. If the current in the wire is $12 \ A$,the magnetic field inside the core of the toroid is:

The magnetic field $B$ within a solenoid having $n$ turns per meter length and carrying a current of $i$ amperes is given by:

$A$ thin hollow copper pipe carries a direct current. Which of the following statements is incorrect?