a) The extended Maxwell's equations would be fully symmetric equations if one allows for the possibility of "magnetic charges" analogous to electric charges.

b) The presence of electric charge was simply "inserted" into quantum mechanics (QM), but in 1931 Dirac showed that a discrete charge naturally "falls out" of QM ... The hypothetical existence of a magnetic monopole would imply that the electric charge must be quantized in certain units; also, the existence of the electric charges implies that the magnetic charges of the hypothetical magnetic monopoles, if they exist, must be quantized in units inversely proportional to the elementary electric charge.

A number of attempts have been made to detect magnetic monopoles. ... there have been tantalizing events recorded, in particular the event recorded by Blas Cabrera on the night of February 14, 1982 (thus, sometimes referred to as the "Valentine's Day Monopole"):
First Results from a Superconductive Detector for Moving Magnetic Monopoles.
by Blas Cabrera
Digital Object Identifier doi:10.1103/PhysRevLett.48.1378
Journal reference: Physical Review Letters 48 (20): 1378-1381.

Yet until now there has never been reproducible evidence for the existence of magnetic monopoles.
Magnetic Monopole Searches
lecture notes by G. Giacomelli, L. Patrizii
Subjects: High Energy Physics - Experiment (hep-ex). Report number: DFUB 2003-1. Cite as: arXiv:hep-ex/0302011v2.
The light yield from a monopole traversing a scintillator is briefly discussed at page 4 of this lecture notes.

Final results of magnetic monopole searches with the MACRO experiment
by The MACRO collaboration: M.Ambrosio et al.
Digital Object Identifier doi:10.1140/epjd/s2002-01046-9
Journal reference: Eur. Phys. J. C 25, 511-522 (2002)
Experimental searches with liquid scintillator system are described in chapters 2.1.1, 2.1.2, 2.4 for monopoles of different velocities.
Theoretical and Experimental Status of Magnetic Monopoles
reviewed recently by Kimball A. Milton
Journal reference: Rept.Prog.Phys. 69 (2006) 1637-1712. Cite as: arXiv:hep-ex/0602040v1
To download this review (84 pages, 23 figures) go to then click on PDF (or on PostScript) in the right-upper corner.
V.Ivanchenko and 2007 summer student M.Vladymyrov implemented the process of energy deposited by classical magnetic monopole passing through matter and delivered Geant4 example:
$G4INSTALL/examples/extended/exoticphysics/monopole which means
geant4.9.1p01/examples/extended/exoticphysics/monopole for $G4INSTALL = geant4.9.1p01
Physics Lists include standard QGSP physics and additional builder for monopole physics.
See $G4INSTALL/examples/extended/exoticphysics/monopole/README for more details.

Popular article in on Oct 2, 2003 about a paper: Z Fang et al. 2003 Science 302 92
Have physicists seen magnetic monopoles?

Web pages about Magnetic Field and Magnetic Field Strength H

Credit to M.Leltchouk, Columbia University, Nevis Labs.