Testing the electric conductivity of liquids in Electrical Conductivity of Liquids – Class 8 Science Experiment

Chapter Name: Electrical Conductivity of Liquids

Activity Name: Testing the electric conductivity of liquids in Electrical Conductivity of Liquids

Activity Description:

Required Items:

1. LED
2. Dry cell (battery)
3. Metal pins
4. Rubber cap from an injection bottle
5. Wires for making connections

Step by Step Procedure:

1. Set up the electric circuit as shown in Figure 2.
2. Ensure that the two metal pins passing through the rubber cap have a small gap of approximately 2 mm between them, making sure they are fairly close but not touching each other.
3. Verify that the LED does not glow when the metal pins are separated by the small distance.
4. Join the free ends of the metal pins together by pressing them for a moment, and make sure that the LED glows.
5. Release the pins to separate them, and the LED should not glow again. This setup becomes our tester for conductivity.

Experiment Observations:

1. Test the electrical conductivity of different liquids one by one, starting with distilled water. Pour distilled water into the rubber cap until it comes in contact with the metal pins. Note whether the LED glows or not.
2. Repeat the procedure for other liquids such as water, coconut oil, kerosene, lemon juice, mustard oil, sugar solution, etc.
3. After testing each liquid, carefully wipe and dry the cap and metal pins before testing the next liquid.
4. Record all observations in Table 2.

Note down your observations in table format:

Precautions:

1. Handle the electrical circuit with care to avoid any electric shocks or mishaps.
2. Ensure that the metal pins have a small gap between them to prevent short-circuiting.
3. Wipe and dry the rubber cap and metal pins before testing each new liquid to prevent cross-contamination and accurate results.

Lesson Learnt from Experiment:

Through this experiment, we will learn about the electrical conductivity of different liquids. Based on the observations, we can infer which liquids are good conductors of electricity and which ones are poor or bad conductors.