Fundamental Physics/Electromagnetism/Electromagnet

Electromagnetic field and its Electromagnetic field intensity

Configuration	Magnetic Field	Magnetic field intensity
For a straight line conductor	circular magnetic field surrounds a point charge along the straight line	$B=LI={\frac {\mu }{2\pi r}}I$
For a circular loop conductor	circular magnetic field surrounds a point charge along the circular loop	$B=LI={\frac {\mu }{2r}}I$
For a coil of N circular loops conductor	lines of magnetic field runs from North pole (Positive polarity) to South pole (Negative polarity)	$B=LI={\frac {N\mu }{l}}I$