Why does a magnetic compass needle pointing North and South in the absence of a nearby magnet get deflected when a bar magnet or a current carrying loop is brought near it. Describe some salient features of magnetic lines of field concept.

An electric current produces a magnetic field.
So, when a current is switched on through a wire, the wire starts behaving as a magnet. When a compass needle is placed near the given current-carrying wire, it gets influenced by the magnetic effect of electric current and gets deflected from its north-south position.

A compass needle gets deflected when brought near a bar magnet because the needle of a compass is a magnet, which experiences a magnetic field exerted by the bar magnet.

$(i)$. The magnetic field lines represent the magnetic field around the magnetic substance or current-carrying conductor with direction and magnitude.

$(ii)$. The magnetic field lines emerge from the North pole and merge at the South pole in a closed curve. 

$(iii)$. The strong magnetic field indicates that the degree of closeness of the field lines is high.

$(iv)$. Two magnetic field lines can never intersect each other.

$(v)$.  A uniform magnetic field in a region is indicated by the parallel and equidistant field lines in a given region whereas converging or diverging field lines indicate the non-uniform magnetic field.


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