2.6　Non-electrical Measurement

In scientific research,industrial and agricultural production,national defense construction,or even daily life,the vast majority of information that people get is non-electric quantity information,which is often difficult to measure accurately.And even if this information is detectable,it is so hard to enlarge,process and transmit.Hence,a special device is often used to detect the relevant information sensitively and accurately and then transform the information into physical quantities which are convenient for processing.It is well known that electrical signals are easy to be amplified,processed,stored and transmitted over a long distance.Furthermore,computers can only process electrical signals.Consequently,most measured non-electric quantities need to be converted into electric quantities for measurement,which forms the electrical measurement technology of non-electrical quantity.This non-electrical quantity measurement is also a kind of conversion measuring method.

The electrical measuring system of non-electric quantity generally includes sensors,measuring circuits,amplifiers,indicators,recorder,and other components.Among all of them,the most critical component is the realization device of variable conversion-sensor.The sensor can convert the non-electric quantity into electrical signals which can be measured by electronic amplification,calculation,display and other devices at a certain level of accuracy.At present,various kinds of sensors,such as resistance type,inductance type,magneto electric type,piezoelectric type,thermoelectric type,photoelectric type,etc.,have been extensively used in related fields.(https://www.daowen.com)

Due to the advantages of high measuring accuracy,fast speed of response,automatic continuous measurements,and convenient long-distance measurements,the application fields of electrical measuring technology of non-electric quantity are becoming wider and wider.Several commonly used electrical measurement methods of non-electric quantity are described as follows.