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Measuring Electricity

What good would all the math be if we never had any numbers to plug in to those fancy formulas? In this article, I'll discuss how we can get some of those numbers we need.

To do that, we typically use something called a multimeter. We might also refer to built in panel meters, or even computer displays. I'll write this with a multimeter in mind; mainly because I'll want to cover how each type of meter is connected.

What is a multimeter?

This is probably self evident, but if we take the name and split the words apart we get multi (meaning many) and meter (meaning measuring device). Thats just what a multimeter is .. many measuring devices conveniently packaged up in one box.

There are two common types of meters; and this will be familiar to most everyone in this digital crazy world. You guessed it, there is analog and there is digital varieties - and the digital is rapidly becoming predominant.

Analog Meters

Analog varieties will have a traditional numbered scale with a moving needle. You will see many rows of numbers on this scale, but don't let that scare you. These are simply appropriate numbers for each of the several things that can be measured by the device. At the end of each row, there will be an indication of the units that row is intended to be used with; and we would look at the row appropriate to what we are measuring.

One additional feature you will notice on most quality meters is a mirror strip. The purpose of that is to verify you are looking straight at the meter. You will want a viewing angle where the needle covers up its reflection in the mirror strip. This insures that you will see the numbers directly under the needle; rather than slightly off to the side of the needle due to viewing at an angle. In some cases, the additional accuracy might not matter .. but its nice to have it when you need it.

Because of our inability to judge the exact needle position, especially between numbers, analog meters may not provide the unambiguous data of a digital readout. Where they do excel is indicating a variable measurement. You can quite easily see a needle moving back and forth, estimate the average reading, and visualize the amount it is changing.

Digital Meters

Like many things digital, the marketing departments want you to believe digital is much better. And, like so many other things in life, often it is. While absolute accuracy is dependant on quality of the device and calibration, digital readouts do provide much less ambiguous numbers to work with. There is no estimating that a needle is half way to the next number, etc. We can simply read the digits and use them.

Digital meters also bring us some features not normally found on analog meters such as automatic range selection, reverse polarity correction (or in many cases operation in reverse by displaying negative numbers), minimum and maximum values, reading hold features, and recording options. Some will even show us a bar graph representing the reading; thus attempting to match the analog meters ability to show changing values.

In the end, which type of meter you will want to use will depend on what you have available and what you are trying to measure. It is nice to have both available; but in most cases you will be able to accomplish your goal regardless of which type you have.

In the next section, we will discuss what all those cryptic looking settings are for ...

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