11.4.1. Activity 11.1

Join the free ends of the tester together for a moment. This completes the circuit of the tester and the bulb should glow. However, if the bulb does not glow, it means that the tester is not working. Can you think of the possible reasons? Is it possible that the connections are loose? Or, the bulb is fused? Or, your cells are used up? Check that all the connections are tight. If they are, then replace the bulb with another bulb. Now test if the tester is working or not.

In this step, we are checking if our tester is functioning properly. By joining the free ends together, we create a complete circuit that allows electric current to flow. If the bulb lights up, it indicates that the circuit is working correctly. If the bulb does not light up, it could be due to loose connections, a burnt-out bulb, or depleted batteries. It’s important to troubleshoot to find the issue, which can include tightening any loose connections or replacing faulty components.

Think of it like checking if a flashlight is working. If you turn on the flashlight and it doesn’t light up, you might check the batteries (like checking the cells in our tester), the bulb (similar to the tester’s bulb), or if the cap is tightly closed (like our connections).

Now that our tester is working, let us use it to test the various liquids. (Caution: While checking your tester, do not join its free ends for more than a few seconds. Otherwise, the cells of the battery will drain very quickly.)

Now that we ensured the tester works, we will use it to test different liquids to see if they conduct electricity. It is vital to remember to connect the ends only briefly, as prolonged contact can deplete the battery quickly. When we dip the tester into the liquids, we are checking whether the liquids allow electric current to flow through them.

Imagine testing your drinks at a party. If you test water, juice, and soda to see which one is fizzy or sweet, you're essentially testing different liquids. In our case, we want to find out which liquids can conduct electricity, similar to discovering which drinks give a strong taste or fizz.

When the liquid between the two ends of the tester allows the electric current to pass, the circuit of the tester becomes complete. The current flows in the circuit and the bulb glows. When the liquid does not allow the electric current to pass, the circuit of the tester is not complete and the bulb does not glow.

This chunk explains how we determine if a liquid is a good or poor conductor of electricity. If the bulb lights up when dipped in a liquid, it indicates that the liquid allows current to pass and is therefore a good conductor. If the bulb stays off, it means the liquid does not conduct electricity, classifying it as a poor conductor. This binary outcome helps us understand the conductive properties of different liquids.

Think about lights in a house; when you flip a switch and the light turns on, electricity is flowing through the wires. If you flip the switch and nothing happens, it means there's a problem—similar to our tester indicating poor conductivity when the bulb doesn’t glow.

In some situations even though the liquid is conducting, the bulb may not glow. It may have happened in Activity 11.2. What can be the reason? Do you remember why the bulb glows when the electric current passes through it? Due to the heating effect of current, the filament of the bulb gets heated to a high temperature and it starts glowing. However, if the current through a circuit is too weak, the filament does not get heated sufficiently and it does not glow. And why is the current in the circuit weak?

Here, we learn that sometimes a liquid may conduct electricity, but if the electric current is too weak, the tester's bulb will not illuminate. This occurs due to insufficient energy being supplied to heat the filament of the bulb. Just because a liquid conducts does not mean it conducts well enough to create a strong current. It’s a reminder to differentiate between mere conductivity and the strength of that conductivity.

Consider water flowing through a garden hose. If you barely turn on the tap, the flow is weak, and not enough water will reach the end of the hose. However, if you turn the tap fully open, a strong stream of water flows. In our tester analogy, we are observing how strong or weak the liquid's conductivity affects the light bulb's glow.

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