Physics can replicate electromagnetic effects with an extremely high degree of precision, it's almost trivial to replicate said effects. Physics has formulated

Physics can replicate electromagnetic effects with an extremely high degree of precision, it's almost trivial to replicate said effects. Physics has formulated models of how electromagnetism works and from that model, predicted other effects that could be replicated in experiments as well. That's what a 'mechanism of action' means here. The predictive power of a model, by whatever means it's formulated makes it useful. There are infinitely many ways to model electromagnetism but only a few of them are useful because they allow to make theoretical predictions that then also match reality.