The plugs with one prong longer--Polarized? I've notice I have bought (more)?

Question

several items of late with out 'polarized' plugs. I think they have something to do with safety & grounding--anyhow, my cell-phone recharger and a personal DVD player both have 'normal' plugs. When are (if they are regulated) polarized plugs required/called for?

Answer 1

There's an excellent article here that explains the purpose of polarized plugs:

http://www.newton.dep.anl.gov/askasci/eng99/eng99158.htm