A circular loop of radius $r$ is carrying current I A. The ratio of magnetic field at the centre of circular loop and at a distance $r$ from the center of the loop on its axis is:

The magnetic field due to a current carrying circular loop of radius $3\, cm$ at a point on the axis at a distance of $4\, cm$ from the centre is $54\, \mu T$. What will be its value at the centre of the loop.......$\mu  T$

A wire carrying current $I$ has the shape as shown in adjoining figure.Linear parts of the wire are very long and parallel to $X-$axis while semicircular portion of radius $R$ is lying in $Y-Z$ plane. Magnetic field at point $O$ is

Do magnetic forces obey Newton’s third law. Verify for two current elements $\overrightarrow {d{l_1}}  = dl\left( {\hat i} \right)$ located at the origin and $\overrightarrow {d{l_2}}  = dl\left( {\hat j} \right)$ located at $ (0, R, 0)$. Both carry current $\mathrm{I}$.

The fractional change in the magnetic field intensity at a distance $'r'$ from centre on the axis of current carrying coil of radius $'a'$ to the magnetic field intensity at the centre of the same coil is : (Take $r << a )$

A non-planar loop of conducting wire carrying a current $I$ is placed as shown in the figure. Each of the straight sections of the loop is of length $2a$. The magnetic field due to this loop at the point $P$ $(a,0,a)$ points in the direction