Understanding of Introductory Concepts of Measurement and Testing and the Meaning of Related Terms and Expressions

Q1.Distinguish between measurement and testing A1.Measurement is defined as the collection of data, the values of certain variables such as resistance, voltage and current may be found at certain points in a circuit or system. These values are obtained using relevant measurement instruments and techniques. Testing is defined as manipulating the values gained during the measurement phase described above to determine whether or not a circuit or system under test is operating correctly …

…so that little current flows through the device, the majority of the current flowing within the circuit or system under test. Conversely ammeters must have a low input impedance as they are connected in series with the circuit or system under test and we do not want a large voltage drop across them. Typical input impedance for a digital device is 10,000,000 ohms per volt. Typical input impedance for an analogue device is 20,000 ohms per volt.