Give Oersted’s observation.
As shown in figure, conducting wire is connected with battery.
Magnetic needle is kept nearby conducting wire which is stable in North-South direction. As key is closed, current in a straight wire caused deflection in a nearby magnetic compass needle and alignment of the needle is tangential of an imaginary circle which has the straight wire as its centre and has its plane perpendicular to the wire. This situation is depicted in figure $(a)$. Here the needle is sufficiently close to the wire so that the Earth's magnetic field may be ignored. Reversing the direction of the current reverses the orientation of the needle which is depicted in figure $(b)$.
The deflection increases on increasing the current or bringing the needle closer to the wire. Moving charges or currents produced a magnetic field in the surrounding space.
A current $I$ flows around a closed path in the horizontal plane of the circle as shown in the figure. The path consists of eight arcs with alternating radii $r$ and $2r$. Each segment of arc subtends equal angle at the common centre $P.$ The magnetic field produced by current path at point $P$ is
A current of $0.1\, A$ circulates around a coil of $100$ $turns$ and having a radius equal to $5\,cm$. The magnetic field set up at the centre of the coil is ($\mu_0 = 4\pi \times 10^{-7} weber/amp-metre$)
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:
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.......$\mu T$
The magnetic field at the origin due to the current flowing in the wire is -