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With analog instruments we measure space, while with digital instruments we measure time!  


Mitko Gorgiev
Member Admin
Joined: 3 years ago
Posts: 42
25/05/2021 12:09 pm  

What do we actually measure when we measure something? All our measurements come down to either measuring space or time. With analog instruments we measure space, whereas with digital instruments we measure time.

Measuring space actually comes down to measuring length. Look please at this instrument for measuring temperature:

What do we measure here? The length of the mercury column in the glass.

The measurements with all digital instruments come down to measuring time. In all electrical instruments we measure only the strength of an electric current (even when we measure voltage, we actually measure current. Please see I have seen a documentary where the weight of a train wagon was measured. The wagon stands on special tracks under which there are electric wires from a special alloy. The electrical resistance of these wires changes under pressure. When an electric current flows through these wires, there is a difference in the magnitude of the current when there is a wagon on the tracks compared to the case when there is not. With an appropriate calibration this difference serves for measurement of the wagon’s weight.

Every electrical measurement comes down to measuring the strength of an electric current and this measurement with digital instruments comes down to measuring time.

How so? The electric current flows through a capacitor. The electricity in the capacitor gets twisted (so I call the charging of the capacitor). It gets twisted to a certain degree. With a stronger current through it, it will get twisted to that degree for a shorter time, while with a weaker current for a longer time. According to the amount of time which is measured with digital counters, the strength of the current through the capacitor can be estimated.

About the digital counters, please see this article:

What are digital logic circuits (an easily comprehensible course on digital electronics)?

So, if you understand that every measurement with analog instruments comes down to measuring length and with digital instruments to measuring time, I believe you will move faster forward in understanding electricity.