Electronics encompasses those things we can neither hear , see, touch,or taste. Electrical voltage,current, and resistance are in-visible to the sense. Of course,You can directly sense an elec-trical shock , but to learn whats going on within an electronic circuit, you must use test equipment. Test equipment is special apparatus designed to give visible or audible indications of what is there and what it is doing . modern test instruments are amazingly versatile. They can do almost anything, if you know how to use them, how they work,and what their imitations are. if you dont know how to use test equipment properly, it is virtually useless. it is also just as important to know what a test instrument cant do. ALL test instruments can make the tests as well, if you know how the instruments work and how their readings can indicate the presence or absence of other electrical parameters.
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