In this topic, you study the methods of measurement.
The methods of measurement are broadly classified as :
(l) Direct comparison methods,
(2) Indirect comparison methods.
(1) Direct Comparison Methods: This is the most common method of measurement used by common man. We measure length, mass etc, of an unknown quantity by comparing it with the known standard. This is not very accurate method; as human errors are involved,
(2) Indirect Comparison or Calibration Methods : The direct method of measurement is not always possible. For accurate measurements and to attain high degree of sensitivity. Indirect methods are preferred.
In indirect method, the quantity to be measured is first converted into a suitable analogous signal. This analogous signal is processed and fed to the instrument for measurement. The device which converts the quantity into the suitable form is called an Instrument Transducer. See Fig. 1.1.
Fig. 1.1. Use of transducer
The signal processing involves the following
(a) Amplification of the weak signal before being given to the instrument or,
(b) Telemetring the data for remote reading e.g. reading temperature of the Sun.
