Energy Spells & Electricity

[Tigrah2k]

Hey all,
I don't think I've asked this question, but my gaming group and I are wondering about the conversion of energy to mana. The magic book is somewhat helpful, but the conversions don't make much sense, and leave far more questions than it answers. Does anyone understand the conversion system well enough to give some notion of how to understand it (relatively simplistically)?

Thanks in advance for any insights.