(a) The pattern of magnetic field depends on the shape of the wire because the magnetic field lines form closed loops around the conductor, and their arrangement follows the geometry of the wire. A straight wire produces concentric circular field lines, while a circular coil concentrates the field at its centre, forming nearly straight parallel lines. Thus, changing the shape changes the overall field pattern.
(b) The magnetic field will be maximum at point X, because X is nearest to the wire. The strength of the magnetic field produced by a current-carrying conductor is inversely proportional to the distance from the wire — closer the point, stronger (more crowded) the field lines and greater the magnetic field strength.
Source: Chapter 12, Sections 12.1 and 12.2
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