In this topic, you study the definition and examples of electrical instruments.
They use electrical methods of measurement and are faster in action than the mechanical instruments. However, the measuring part of these instruments is also mechanical consisting of needle, spindle, springs etc. Their accuracy and sensitivity are no doubt superior than the mechanical instruments, but not so much as to cope with the modern days requirements. They can measure a quantity varying at the rate of 50 Hz per second or 60 Hz per second. The ammeters, voltmeters are the examples of these instruments. The (Fig. 1) shows an ammeter.
Fig. 1. Ammeter