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Conductivity tester

Intermediate | MakeCode | LED display, Pins, Sound | Electricity, Iteration, Selection

Step 1: Make it

What is it?

Use your micro:bit with two crocodile clip leads to investigate if a material conducts electricity - a simple way to carry out a classic science experiment!

How to use it

  • Transfer the code below to your micro:bit, or watch the coding video above if you want to create the code yourself.
  • At the bottom of a micro:bit are five large pins. When you connect pin 1 and the GND or ground pin with a crocodile clip lead, it completes an electrical circuit.
  • Safety note - never connect the GND and 3V pins directly together or you may damage your micro:bit.
  • If you attach two crocodile clip leads, one to pin 1 and one to the GND pin, you can put a material such as silver foil or cling film between the ends of the two leads to test if the material is conductive or an insulator.

How it works

  • The project uses selection. If an electrical circuit is made (because the material conducts) then the micro:bit will show a heart on its LED display and play the note Middle C.
  • Else, if a circuit is not made, the micro:bit will clear its LED display and a note will not play - the micro:bit is instructed to play a note at a frequency of 0Hz.
  • The program uses a forever or infinite loop to keep on testing until you disconnect your micro:bit from a power supply.

What you need

  • micro:bit (or MakeCode simulator)
  • MakeCode editor
  • battery pack (optional but recommended)
  • our pins introduction video may be useful

You may like

The Conductivity tester recording sheet can be used to record which materials conduct and which do not in a classroom or coding club.

Conductivity tester recording sheet
Download the recording sheet

Step 2: Code it

1from microbit import *
2import music
4while True:
5    if pin1.is_touched():
8    else:
9        display.clear()

Step 3: Improve it

  • Adjust the code to show a different icon or play a different sound if the material is conductive.
  • Try out a wide range of materials with your conductivity tester such as pencil graphite, PlayDoh, and dry and damp tissue paper.
  • It can be fun to use a human being as the test material! Simply hold the crocodile clip leads in both hands, or form a human chain.