In contrast to alternating current, or AC, which, depending on the supply's frequency, switches direction 50 or 60 times per second, the current in DC circuits flows only in one direction.

AC and DC Current: AC (Alternating Current) and DC (Direct Current) are the two fundamental forms of electrical current, differing in how electricity flows through a circuit. Understanding this ...

Extech Instruments announces its MA640 600A True RMS AC/DC Clamp Meters + NCV that has a higher accuracy rating then standard RMS meters.