{"id":64653,"date":"2026-06-20T04:42:21","date_gmt":"2026-06-19T19:42:21","guid":{"rendered":"https:\/\/phys-edu.net\/wp\/?p=64653"},"modified":"2026-06-20T04:42:21","modified_gmt":"2026-06-19T19:42:21","slug":"why-start-at-5a-how-analog-ammeters-work-and-why-the-digital-petit-meter-changes-everything","status":"publish","type":"post","link":"https:\/\/phys-edu.net\/wp\/?p=64653&lang=en","title":{"rendered":"Why Start at 5A? How Analog Ammeters Work\u2014and Why the Digital “Petit Meter” Changes Everything!"},"content":{"rendered":"

I\u2019m Ken Kuwako, a science trainer. Every day is an experiment.<\/strong><\/span><\/p>\n

There are things we cannot see with our eyes, yet they definitely exist. One of them is \u201celectric current.\u201d Turn on a switch and a light comes on. A motor starts spinning. But what exactly is electric current?<\/span><\/p>\n

After learning circuit diagrams, the next step is learning how to use an ammeter. In the third lesson on electric circuits, we first explored what electric current actually is. Using small light bulbs and LED bulbs, we tested what happens when the connections from the positive and negative terminals of a battery are switched.<\/p>\n

The result was fascinating. The small bulb worked the same way in either direction, but the LED bulb changed \u2014 it lit up in one direction and turned off when reversed. At this point, students began to realize, \u201cMaybe something is flowing in only one direction?\u201d When we tried the same experiment with a motor, the direction of rotation changed when the connections were reversed. From this, students discovered that electric current has a direction. However, at this stage, we still do not know exactly which way it flows.<\/p>\n

Another question naturally comes up: \u201cHow much electric current is flowing?\u201d This is where the ammeter enters the story.<\/p>\n

Meeting the tool that measures the \u201camount\u201d of electric current<\/h3>\n

Since ammeters also appear in their textbooks and workbooks, I explained how to use an analog ammeter. Our school also has mini digital ammeters called \u201cPetit Meters,\u201d so I told the students that this would be their one and only chance to practice using an analog meter. One of the fascinating things about science is that measurement tools continue to evolve with the times<\/strong>.<\/p>\n

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DC Ammeter Petit Meter CT-A Compact Digital Ammeter<\/a><\/p>\n

Once again, the key is to \u201cuse your hands and try it yourself.\u201d First, I had each group bring out a circuit kit. This time, each group shared one set.<\/p>\n

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Using an analog ammeter, students actually built circuits and confirmed how to connect the ammeter correctly \u2014 placing it in series within the circuit.<\/p>\n

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I also explained how to use the negative terminals: always start from the largest range, 5A<\/strong>, then move down to 500mA and 50mA while checking the readings. I also taught them to read down to one-tenth of the smallest scale division<\/strong>.<\/p>\n

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After that, I handed out the Petit Meter ammeters and explained that we would use these from now on. With the Petit Meter, there is no need to struggle with reading scales \u2014 students simply read the value displayed on the screen. Some students who had struggled with the analog meter looked relieved.<\/p>\n

Experiencing the \u201cpower of electric current\u201d with a hand-crank generator!<\/h3>\n

One activity I highly recommend is connecting a hand-crank generator to an ammeter<\/strong>. Instead of using a battery, students create electricity using their own strength. This helps them truly feel, \u201cWow, electric current actually has this much power!\u201d<\/p>\n

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First, we connect the generator to the largest range of the ammeter, 5A, and turn the handle. No matter how hard students try, the needle only moves slightly. But when we change the connection to 500mA or 50mA, everything changes. There is one important rule here: turn the handle slowly.<\/p>\n