ANALOG DEVICES: CURRENT MEASUREMENTS
Direct Current
One way to measure a DC electrical current is to use an analog device that responds to the force
exerted on a current-carrying conductor in a magnetic field. Because an electric current is a series of
moving charges, a magnetic field exerts a force on a current-carrying conductor. This force can be
used as a measure of the flow of current in a conductor by moving a pointer on a display.
Consider a straight length l of a conductor through which a current I flows, as shown in
Figure 6.1. The magnitude of force on this conductor due to a magnetic field strength B is