Verification of a voltage reading is performed using a "low-impedance" voltmeter, which usually has a shunt resistor load bridging the voltmeter terminals. Since very little current can flow from a coupled surface through the small shunt or meter resistance, capacitively coupled voltages will collapse to zero, indicating a harmless "false alarm". By contrast, if an object being tested is in contact with a current source, or coupled by a very large capacitance (possible but unlikely in this context), the voltage will drop only slightly as dictated by Ohm's Law. In this latter case, real power is being delivered, indicating a potentially hazardous situation.