In this lesson we will create a circuit so that with a switch you can turn an LED on/off. As a bonus you can optionally add a component to control the brightness.
For a child this is about flow of electricity. This can be explained as water flowing in the garden hose from the faucet to the nozzle. The faucet is like the “+” or positive end on a battery, “-” or negative being the nozzle and the hose being the wire. Electricity must flow from positive through the components you connect and finally must end in the negative.
Let us introduce a breadboard. In a breadboard on the left and right are the “+” and “-” columns where we will connect the power. In the center for each row as highlighted below the holes 2a to 2e are connected together and 2f to 2j are connected together. So for example if wires are plugged into 2a and 2e then they will be connected.
The next component we need is a power supply. This could be a 9V battery or a supply with a USB connector. This provides electricity for our experiment. If you have a multi-meter you may use it to check.
Next we need a LED and switch which should be familiar for a child as any household light and switch.
Another component to introduce is a resistor. It reduces the flow of electricity. Its like squeezing your garden hose so less water comes out of the nozzle. The bigger the number, the harder the squeeze and lesser electricity will flow across it. We need this to reduce the amount of electricity that flows through the LED otherwise it will burn out.
If the child inquires what is the Ω symbol you may mention its the Greek letter Omega for measuring resistance in Ohms. Similarly V for Volts but this is not necessary for what we are doing.
Have the child explore these components and try to connect them as shown. You can help by pointing the number to put a particular pin in.
Tip: Make sure the positive and negative pins of the LED are connected correctly. Switch it around in case it does not work. The long leg should be positive.
You can plugin multiple LEDs with different resistors and see LEDs with different brightness.
Bonus: finally, if you have a potentiometer, which is a variable resistor then use it instead of the fixed resistor. You can now turn its knob to see the LED brightness change.
In the next lesson we will learn about transistors.