Current is flowing through a conducting hollow pipe whose area of cross-section is shown in the figure. The value of magnetic induction will be zero at
points $P, Q$ and $R$
point $R$ but not at $P$ and $Q$
$Q$ but not at $P$ and $R$
$P$ but not at $Q$ and $R$
Find magnetic field at $O$
$AB$ and $CD$ are long straight conductor, distance $d$ apart, carrying a current $I$. The magnetic field at the midpoint of $BC$ is
The earth's magnetic induction at a certain point is $7 \times {10^{ - 5}}\,Wb/{m^2}.$ This is to be annulled by the magnetic induction at the centre of a circular conducting loop of radius $5 \,cm$. The required current in the loop is......$A$
In the diagram, $I_1$ , $I_2$ are the strength of the currents in the loop and infinite long straight conductor respectively. $OA = AB = R$ . The net magnetic field at the centre $O$ is zero. Then the ratio of the currents in the loop and the straight conductor is
At what distance on the axis, from the centre of a circular current carrying coil of radius $r$, the magnetic field becomes $1 / 8$ th of the magnetic field at centre?