Voltage
What voltage actually is, how it differs from current, the symbols and units used for it, and how to measure it safely with a multimeter.
Questions people ask
What is the difference between voltage and current?
Voltage is the push; current is the flow that results. In the water analogy, voltage is the pressure and current is the litres per second actually moving through the pipe.
Does higher voltage mean more dangerous?
Voltage determines whether current can overcome your skin's resistance, but it is the current through the body that causes harm. Roughly 50 V is where mains-frequency AC starts being treated as hazardous.
Why is mains voltage quoted as RMS?
Because the RMS value is the DC voltage that would deliver the same heating power. It makes AC and DC figures directly comparable for power calculations.
Does this page work offline?
Yes, after the first visit. The service worker caches it, so the reference stays available with no connection.
Last updated 22 August 2026