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

and the voltage drop across the resistor is measured. If the resistance also is known, the current can be calculated with the equation I=V/R. This simple fact can be used to great effect.

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 ...

Voltage is the pressure that forces electric current to flow though a wire. In North America, utility systems typically ...