ABSTRACT
This chapter discusses and names the electrical measuring instruments used to measure current, voltage and resistance. It explains how an ammeter and a voltmeter must be inserted into a circuit in order to measure electric current and voltage. The chapter also explains how an ohmmeter is used to measure resistance and describes the main construction features of a moving-coil instrument, together with the function of each. The 'moving-coil', or 'd'Arsonval', movement is the most common type of meter movement employed by precision analogue instruments such as ammeters, voltmeters, ohmmeters and multimeters. Voltmeters must always be connected in parallel in a circuit, and have a very high internal resistance. The gate is controlled by a digital circuit which converts the test voltage to time, with that time being directly proportional to the test voltage. An analogue multimeter is a moving-coil instrument that can measure both direct current and alternating current and voltages, together with resistance.
