14.16 of Olson, differential transformer. Two GFIs procured from Home Depot. There's still the same area facing the B field lines. Shielding by metal foil. More difficult to shield for magnetic fields.
Shielding means surrounding of a cable by a metal foil one side of which is grounded .
A 1M resistor will pick up or generate much more noise than a 1K resistor. Another, lower the output impedance of devices that must drive long transmission lines. If not much at all, then output impedance is low. EM radiation, including x-rays, falls into the category of electrical hazard. 14.12, micro-shock hazard.