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

Lesson Overview:

## Step 1: Introduction

The Voltage Park is a steep hill. The height of the hill is 9 volts, to be exact!

What do we mean by this?

An electrical circuit is a lot like a hill. A battery supplies potential energy to the circuit and as current flows through it, it flows from points of high voltage to points of low voltage.

This is a lot like a golf ball rolling down a hill. The ball naturally moves from taller heights to lower heights.

1. Press the "next" button below to continue.

## Step 2: Understanding a Contour Map

A contour map, or a "topographical" map, uses lines and color to represent elevation in a landscape.

It's a way of showing hills and valleys while still being able to use a flat piece of paper or computer screen.

Check out the contour map of Hawaii Island, below. There are loops of wavy contour lines around two volcanos.

Any points along the same line on the contour map have the same elevation (height). The color between two lines shows elevation -- so we can glance at the map and see where hills and valleys are!

1. Press the "next" button below to continue.

## Step 3: Understanding a Voltage Landscape (part 1)

In our circuit-landscape analogy, voltage is like elevation. Anywhere you have traces (lines, wires) touching each other, you have the same voltage!

Recall the "Row of Houses" circuit, or the LEDs in parallel. The circuit only had two lines in it, which we called voltage rails. The entire top line was at 9V, and the entire bottom line was at 0V. (See picture)

1. Press the "next" button below to continue.

## Step 4: Understanding a Voltage Landscape (part 2)

Let's start placing components in the Workplane.

Start by placing the battery on the two horizontal pads on the left side.

The battery sets the maximum and minimum voltages in the circuit, or the "height" of the contour map.

1. Open the Modules + window and drag a battery into the Workplane.
2. Rotate the battery so the module lies horizontally and the positive terminal faces to the right.
3. Snap the battery module onto the left-most set of pads spanning the inner and outer loops (see picture).
4. Continue to the next step.

## Step 5: Understanding a Voltage Landscape (part 3)

What is the voltage of the smallest, inside loop? (see hint)

What is the voltage of the largest, outside loop? (see hint)

1. Open the Modules + window and drag a battery into the Workplane.
2. Rotate the battery so the module lies horizontally and the positive terminal faces to the right.
3. Snap the battery module onto the left-most set of pads spanning the inner and outer loops (see picture).
4. Continue to the next step.

## Step 6: Rolling Down the Hill

Now the total elevation of the park is set! How do we set the heights of the other three contour lines?

We do this using components.

In a circuit, every time current encounters a component, there is a drop in the voltage level across that component.

All of the voltage drops on a path between the battery terminals add up to the battery voltage. (Find the lesson on Kirchoff's Laws for more detail.)

We set the voltage levels of each contour line in the Workplane by placing an LED, resistor, or switch across the remaining contour lines.

1. Open the Modules + menu and bring three LEDs and a switch into the Workplane.
2. Snap the switch onto the two pads that are oriented horizontally.
3. Rotate the three LEDs so their orientation matches the other pads. Snap them into place. (see picture)
4. Simulate the circuit and flip the switch on and off!
5. Press the "next" button below to continue.

## Step 7: Modifying the Contour Map

Before printing out the voltage park (in the next step) you can modify the circuit by changing the shape of the circuit scribe traces.

Stop the simulation and highlight one of the circuit traces. Several light green lines with "handles" pop up that you can drag around the workplane.

The middle of the handle moves the location of the curve. The two outer handles change its shape.

What happens if two of the contour lines touch? (see hint)

1. Click on the middle of one of the handles and try dragging it around.
2. Now click on the end of one of the handles and move it. What happens?
3. Continue modifying the shape of the contour map but make sure the lines don't cross each other!
4. You can press the "undo" button or type control-Z to go back one step.
5. Press the "next" button below to continue.
6. Stuck? HINT: If two of the lines touch, they will have the same voltage - and there will not be a voltage drop across the component between them. This connection is called a "short."

## Step 8: Printing the Template

Now you have a template that you can use in your City of Lights model!

Print out your template by clicking "Download PDF" and printing out the file. Watch the video tutorial in the next lesson to learn how to build your voltage park.

Next Lesson:Voltage Park Video