$A$ solenoid of length $50 \,cm$ having $100$ turns carries a current of $2.5 \,A$. The magnetic field at one end of the solenoid is

$A$ solenoid of length $50 \ cm$ and radius $10 \ cm$ has two closely wound layers of windings, each with $100$ turns. If a current of $2.5 \ A$ is passing through the windings, the magnetic field (in $10^{-4} \ T$) at a point $5 \ cm$ from the axis is:

$A$ closely wound solenoid of length $1 \,m$ has $5$ layers of $500$ turns each. If the magnitude of the magnetic field inside the solenoid near its centre is $4.4 \,mT$, the current carried is: (in $\,A$)

In a co-axial straight cable,the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero:

The magnetic field inside a long solenoid is:

$A$ closely wound solenoid of $80 \,cm$ long has $5$ layers of windings of $400$ turns each. The diameter of the solenoid is $1.8 \,cm$. If the current carried is $8 \,A$, then the magnitude of the magnetic field inside the solenoid near its centre is approximately