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 silent features of magnetic lines of field concept.

Explanation

Current -carrying loops behave like bar magnets and both have their own magnetic field lines. This modifies the already existing Earth.s magnetic field and a deflection results. Magnetic field has both direction and magnitude. Magnetic field lines emerge from N-pole and enter S-pole. The magnetic field strength is represented diagrammatically by the degree of closeness of the field lines.
Field lines cannot cross each other as two values of net field at a single poiint cannot exist. Only one value, a unique net value, can exist. If in a given region, lines of field are shown to be parallel and equi-space, the field is understood to be uniform.