Why? For current to flow, it must overcome the body’s resistance, which requires sufficient voltage. A car battery’s 12 volts simply aren’t strong enough to push enough current through the body.

You need to know how to measure the current that flows through a component in a circuit and the voltage across it. The ammeter must be connected in series with the component – remember ...

which defines the relationship between current, voltage, and resistance. If we know two out of the three, we can calculate the unknown. This is the underlying principle behind the current shunt.

The r.m.s. value of an a.c. signal is equal to the value of direct current (d.c.) which would have the same effect or energy change as the a.c. The r.m.s. voltage of an a.c. signal is always less ...

Laura is an Assistant Editor for The Scientist. She has a background in microbiology. Her science communication work spans journalism and public engagement.