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The current sensor

This page was translated from German with AI. It has not been checked by a native speaker. Original page in German

The current sensor measures the current. It has no display of its own; it sends its values by Bluetooth to an app on the tablet. Here you learn how it goes into the circuit – and how it does not.
📄 Open worksheet (PDF, German)

The video

In the video the sensor is built into a circuit of plug-in blocks. The yellow dots show where current flows.

Subtitles are available in ten languages. Choose them at the bottom right of the video.

Contents of the video

  1. 0:00 Overview
  2. 0:12 The parts
  3. 0:26 In series
  4. 0:47 Measuring range
  5. 0:53 Caution
  6. 1:06 In short

The most important points

No display of its own: you see the measured value in the app.
No display of its own: you see the measured value in the app.
On top there is a blue and a red socket. The button at the front switches it on; the light on the left belongs to Bluetooth, the one on the right to the battery.
On top there is a blue and a red socket. The button at the front switches it on; the light on the left belongs to Bluetooth, the one on the right to the battery.

In series

The current has to go through the sensor. Open the circuit at one point and put the sensor into the gap. If the app shows a minus, the cables are just swapped – that does no harm.

The sensor measures up to 1 A, as it also says on the device.

Never directly on the power supply and never next to a lamp: then far too large a current flows through the sensor. Before re-plugging, switch the power supply off.
Never directly on the power supply and never next to a lamp: then far too large a current flows through the sensor. Before re-plugging, switch the power supply off.

The worksheet

Here you can see the worksheet for the video (in German). The hints are printed upside down – turn the sheet only when you cannot get on by yourself. You can also open it as a PDF.

📄 Open worksheet (PDF, German)

The worksheet – Page 1
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The worksheet – Page 2
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The worksheet – Page 3
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Show the worksheet solutions
The worksheet – Page 4
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Try it yourself

Task

a) The app shows −0.25 A. What does that mean? b) Someone plugs the two cables of the sensor left and right of the lamp. What is wrong with that?

Show solution

a) 0.25 A is flowing, just the other way through the sensor: the cables are swapped, which does no harm. b) The sensor is then next to the lamp instead of in series. The current flows through the sensor instead of through the lamp – far too much for it. It belongs in a gap in the circuit.

Keep learning with a language model

You are my physics teacher. I am learning to measure current with a current sensor: it goes in series, into a gap in the circuit; a minus means it is connected the other way round; never directly on the power supply. Explain to me with a comparison from everyday life why the sensor has to be connected in series. Then ask me two questions and wait for my answers.

How this was made: The idea and the choice of equipment are mine. A language model (LLM) drafted the script, the drawings, the worksheet and this page following my instructions. The devices are drawn from photos of our collection and from my own templates. The voice was generated with Qwen3-TTS, modelled on my own voice.

Limits and operation apply to the devices in our collection. If you work with other devices, follow what is written on the device and what your teacher says.

The videos, worksheets, texts and prompts in this series are licensed under CC BY 4.0: you may use, change and share them if you name the source.