Two insulated circular loop $A$ and $B$ radius ' $a$ ' carrying a current of ' $\mathrm{I}$ ' in the anti clockwise direction as shown in figure. The magnitude of the magnetic induction at the centre will be :
$\frac{\sqrt{2} \mu_0 I}{a}$
$\frac{\mu_0 I}{2 a}$
$\frac{\mu_0 I}{\sqrt{2} a}$
$\frac{2 \mu_0 I}{a}$
An element $\Delta l=\Delta \mathrm{xi}$ is placed at the origin and carries a large current $\mathrm{I}=10 \mathrm{~A}$. The magnetic field on the $y$-axis at a distance of $0.5 \mathrm{~m}$ from the elements $\Delta \mathrm{x}$ of $1 \mathrm{~cm}$ length is:
A current $i$ ampere flows in a circular arc of wire whose radius is $R$, which subtend an angle $3\pi /2$ radian at its centre. The magnetic induction at the centre is
The magnetic field at a distance $r$ from a long wire carrying current $i$ is $0.4\, Tesla$. The magnetic field at a distance $2r$ is......$Tesla$
Figure shows a square loop $ABCD$ with edge length $a$. The resistance of the wire $ABC$ is $r$ and that of $ADC$ is $2r$. The value of magnetic field at the centre of the loop assuming uniform wire is
A circular coil of wire consisting of $100$ turns, each of radius $8.0\; cm$ carries a current of $0.40\, A$. What is the magnitude of the magnetic field $B$ at the centre of the coil?