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Lesson Overview:

Now we'll learn about batteries and voltage!

Step 1: Introduction

In this lesson we will introduce the concept of voltage: a source of energy that enables current to flow around a circuit. This lesson will use the multimeter again.

In previous lessons we have thought about current moving around a circuit being similar to cars driving around town. In order to move, current needs some source of energy that gives it a push -- kind of like the gas in your car. In our circuits, that push is provided by the battery.

Continue on to the next step for another voltage analogy: a set of stairs.

Step 2: Going Down a Voltage Staircase

Imagine that you stand at the top of a flight of stairs and put a ball at your feet. Give it a small push. The ball would roll down the stairs! In order to get back to the top of the stairs you have to use some energy, like sending it up an elevator, or having a friend toss it to you.

Voltage for your circuit does the same thing. Current moves from points of high voltage (the top of the stairs) to points of low voltage (the bottom of the stairs).

In a circuit, you can think of the top of the stairs being the positive terminal of the battery. As current flows through the circuit, it is trying to get to the ground floor in the easiest way possible. Every component that it encounters is a step in the staircase at a lower voltage. In fact, the negative end of the battery - with zero voltage - is actually called “Ground.”

In the next step, you will measure the “elevation” that each battery in our library can provide.

Step 3: Measuring Voltage

Voltage is measured across or “in parallel” with a component. You are measuring a voltage drop, or a change in elevation, from one side of a component to another.

In this step, you will measure the voltage drop across the terminals of the batteries that we have available to us.

Coin cell battery: 3 Volts AA battery: 1.5 Volts 9V battery: 9 Volts

  1. Open the component library by pressing the Components + button
  2. Find the multimeter tool, which looks like a yellow box, and drag it into the Workplane
  3. Hide the component library.
  4. Position the multimeter over the 9V battery
  5. Hover your cursor over the multimeter terminals to figure out which terminal is positive (red) and negative (black).
  6. Connect a wire from the positive terminal of the multimeter to the positive terminal of the battery.
  7. Connect a second wire from the negative terminal of the multimeter to the ground (negative) terminal of the battery.
  8. Make sure the multimeter is in voltage mode by highlighting it and choosing “voltage” from the drop down menu.
  9. Simulate the circuit! What is the voltage reading?
  10. Before moving onto the next step, try the same process with the coin cell and AA batteries. What are the voltage readings?

Step 4: Adding Voltages (part 1)

What if 9V isn’t a high enough voltage for your circuit? In order to increase the total voltage available to the circuit, you can add batteries together in series.

You can try it using two AA batteries in series.

Voltages simply add in series. 1.5 V + 1.5 V = 3 V

If you have more batteries, they continue adding together: V1 + V2 + V3…

  1. Copy the AA battery by highlighting it and typing control or command-C on your keyboard.
  2. Rotate the new battery so the + end is facing down by typing the r key.
  3. Connect the bottom terminals together with a wire.
  4. Connect the terminals of the multimeter to the top terminals of the batteries, matching positive and negative terminals together.
  5. Simulate the circuit. What is the voltage reading?

Step 5: Adding Voltages (part 2)

In this step, we will look inside the battery.

How many AA batteries would need to be added together to create a 9V battery? (see hint)

If you were to look inside a 9V battery, this is actually how the battery is put together. Six 1.5 V batteries or “cells” are connected in series to add up to 9 volts. In fact, the symbol for a 9V battery looks a lot like a stack of cells:

  1. Copy the AA battery by highlighting it and typing control or command-C on your keyboard.
  2. Rotate the new battery so the + end is facing down by typing the r key.
  3. Connect the bottom terminals together with a wire.
  4. Connect the terminals of the multimeter to the top terminals of the batteries, matching positive and negative terminals together.
  5. Simulate the circuit. What is the voltage reading?

Step 6: How Can You Make a Custom Voltage Source?

You can add different types of batteries together as well.

What if you are working in the circuit simulator, and your circuit requires 12 volts -- how many different ways can you add batteries together to get 12 Volts? Start with the 9 V battery and add to it. Can you do it with just coin cells? (see hint)

In the time you have remaining, try adding batteries in series in the simulator and measuring the voltage.

Congratulations on learning a new function of the multimeter! In the next lesson you will learn how to control and direct the flow of current in a circuit using buttons.

Next Lesson:Control Current Flow with Buttons

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