# How to Make a Simple Circuit With a Light Bulb

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The following information is a single lesson in a larger project. Find more great projects here.

Project Overview:

Starting with household items: a light bulb and a battery, the student is walked through the basics of electricity. The first lesson teaches how to make a light bulb light up. The second lesson shows how to make LEDs light up and uses a breadboard to hold everything together.

## Step 1: Hello Electricity

Electricity, some people can’t imagine a world without it, and yet to most people electricity is something mysterious that makes light and powers our cell phones. In other words something only magicians and engineers can understand…

Today we reveal the magic! With the right mindset and tools anyone of any age can understand electricity and have fun doing so. You’ll start off simple with light bulbs and work your way up to electronic circuits! Click on the Next button below to get started.

Instructions

1. Continue to the next step.

## Step 2: Your First Circuit

We can’t see electricity, but it is a type of energy, just like heat from a fire, movement of a motor or light from a light bulb or the sun.

A light bulb is simple device that converts electrical energy into heat and light.

Since we can see light, making a circuit with a light bulb it’s a great way to look for electricity.

Now you’ll make a simple circuit to demonstrate. You need a source of electrical energy: a battery, and a small light bulb.

Instructions

1. Click the Components+ button, notice new parts appeared at the bottom.
2. Search for the 9V battery and click it once to add it to your circuit. Place the battery in the middle of the screen. This is called the work plane.
3. The battery is sideways. You want it straight up so click it once to highlight it (a black outline will appear).
4. Press the “R” key or the Rotate button so the battery’s terminals point up.
5. If you click the Components+ button again the components menu will hide.
6. Click again on the Components+ button, search for the light bulb and add it above the battery you just placed.
7. Continue to the next step.

Electricity can be thought of like water that flows through pipes. It’s time to add wires between the battery and the light bulb so electricity can flow between them.

This flow is called “current”. To connect the battery and light bulb with wires follow the steps. In 123D Circuits every component has "terminals". Terminals are special places where you can connect things.

Instructions

1. The battery terminals are the small metal pins on the battery - they are next to battery\u2019s red and black areas. Hover over the terminal that's connected to the red part of the battery and a red box appears. This indicates where you can start a wire.
2. Click on the left (+ positive, red) terminal of the battery and move your mouse around: a wire is now connected to your mouse.
3. If objects seem too small to select - use your mouse to zoom in and out until the components are big enough to easily click the terminals.
4. Now click on the left terminal of the light bulb (called "terminal 1") to connect the wire to the light bulb. You have just connected the bulb to the battery with a wire!
5. You still need a second wire to complete the loop - so now connect the black terminal of the battery to the right terminal of the light bulb in the same way.
6. Continue to the next step.
7. Stuck? HINT: To change the color of a wire: click once on a wire and choose a different color in the top left corner drop-down.

## Step 4: Turn on the Simulation

Your circuit should now have a battery, a light bulb, and two wires. If your circuit does, congratulations!

It is now time for you to turn on the circuit and let “current” flow through the battery, through the wires, and through the light bulb to make light.

It’s all happening on a computer screen, so when we say “turn on” the circuit we use the word “simulate.”

The computer will “simulate” a real circuit and in this case you hope to see the light bulb light up

Instructions

1. To turn on the light bulb click the “Start Simulation” button in the upper right corner of your screen. The light bulb should light up.
2. To turn off the light you can pause the simulation by clicking the “Stop Simulation” button.
3. Continue to the next step.

## Step 5: More About Current

One of the fundamentals of electricity is that current always flows in a loop. It always comes back to where it started.

If you “break” the circuit the current will not be able to flow in a loop and will stop.

You can break your circuit by deleting one of the wires. If you do delete a wire then click “Start Simulation” the light bulb will not light up.

Instructions

1. To delete a wire you must first stop the simulation. If it's running press the "Stop Simulation" button.
2. Click on one of the wires and press Delete on your keyboard or garbage icon in the upper left of your screen.
3. Click the Start Simulation button to see what happens. Removing the wire broke the circuit so that current was not able to return to the battery.
4. Now redraw the wire and see what happens when you start the simulation again.
5. Continue to the next step.

## Step 6: The Light Switch

In the last step you turned on and off the light bulb by breaking and re-connecting the loop.

This is also how the light switches in your walls turn on and off the lights.

The picture below shows an example of what a switch looks like. Next to the picture of the switch is what we call a “schematic symbol” of the switch: it explains how the switch works on the inside.

The switch has three terminals but only two are ever connected at the same time: 2&1, or 2&3.

The default position is 2&3.

Instructions

1. Continue to the next step.

## Step 7: Add a Switch

Now add the switch. In 123D Circuits we call it a “slide switch” because it slides between two different positions.

In this step try to copy the image below as closely as possible.

Instructions

1. Delete the wire from the + (red) battery terminal to the left terminal of the light bulb.
2. Click the Component+ button and find the slideswitch. Add the slideswitch by clicking it once.
3. Use the Rotate tool to orient the slideswitch like it’s shown above (vertically, terminals pointing to right).
4. Connect a wire between the battery’s + (red) terminal and the #2 (middle) terminal of the switch.
5. Connect a wire between the #3 (top) terminal of the switch to the left terminal of the light bulb.
6. Start the simulator by pressing “Start Simulation.”
7. With the simulation running, click the slideswitch.
8. Continue to the next step.

## Step 8: Experiments

You just finished your first interactive circuit with simulation!

Now experiment with what you’ve learned by changing things.

Instructions

1. See the image above? You could go crazy and add more to your circuit too!
2. What would happen if you change the wire from the light bulb's left terminal and connect it to terminal 1 of the switch (the bottom) instead of terminal 3 (the top)?
3. Delete all wires and move the switch to the left side between the battery’s red terminal and light bulb’s left terminal. Re-wire the circuit. Will this change it’s behavior or is it the same?
4. Swap the terminals of the light bulb so the wires cross like an "X". Will the circuit behavior change?
5. Add a second switch or even a second light bulb. How many can you add?
6. Congratulations! You've completed this lesson.

In the next lesson you will learn about breadboards and powering LEDS.

Next Lesson:How to Use a Breadboard to Light LEDs

## Recommendations

• ### Large Motors Class

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