SCI Kit | Build a Conductivity Tester

Introduction：

Have you ever noticed that the electrical wires for household appliances are usually covered in plastic, while their power plugs are made of bare metal? The reason for this is simple: the metal core is used to transfer electrical power, while the plastic covering insulates the metal part from human contact, preventing electric shock. But have you ever wondered how electricity flows through different materials, and why some materials conduct electricity better than others? Today, we'll be exploring the fascinating world of conductivity.

In this project, you will learn how to connect the SCI module and the soil moisture sensor to make a conductivity tester, and how to interpret the readings obtained. 

Knowledge：

1. SCI DAQ Module

wiki: Gravity: SCI DAQ Module

The SCI DAQ module is a multi-functional data acquisition module that is designed to convert analog signals into physical quantities, which offers a convenient and accurate way to observe and collect data in real-time. The term "SCI" stands for science. If you are using the module for the first time, please refer to the SCI wiki page.

2. Soil Moisture Sensor

wiki: Gravity: Analog Soil Moisture Sensor

The soil moisture sensor has two separate golden probes. When they are connected by conductive objects, the circuit is completed and electricity can flow. The sensor is typically used to check the moisture level of soil because wetter soil conducts electricity more easily. Consequently, we can determine the conductivity of materials by comparing the voltage detected by the sensor.

Materials:

SCI DAQ Module x 1

SEN0114 Soil Moisture Senor x 1

3pin Wire x 1

Type-C Cable or Battery

Testing Items (e.g., scissors, eraser, etc.)

Setup:

1. Power the SCI module from either battery or Type-C port.

2. Connect the soil moisture sensor to the left Port 1.

3. Press the S button to enter the setting menu.

4. The cursor stays at the Select SKU by default, press the OK button to enter the sensor selection page.

5. Use S and R button to select Analog, press OK to confirm.

When Analog is selected, the voltage value read from port 1 will be displayed on the initial page, unit mV.

Experiment:

Find some everyday stuff of different materials, such as scissors, eraser, or even your own finger! Test an item by laying it across the sensor probes, observe the data reading on the screen and write the number down in the chart below.

1. Set up the Experiment

2. Record the Data

Data Analysis:

After conducting the tests and recording the data, categorize the items into two groups based on their conductivity. Use the data obtained from the sensor probes to determine which items are good conductors and which are poor conductors.

Conclusion:

Through the experiment, it has been observed that electrical power can flow through certain materials such as metals and the human body. These materials are known as conductors, and they are characterized by their ability to conduct electricity. Conversely, materials such as plastic are not able to conduct electricity and are known as insulators. The ability of a material to conduct electricity is dependent on its physical properties, such as the number and mobility of its electrons. Conductors typically have a high number of mobile electrons, while insulators have very few mobile electrons. The distinction between conductors and insulators is an important concept in electrical engineering, and it has significant practical applications in the design and construction of electrical circuits and devices.