#### Adding Light Bulbs in Series and Parallel

The goal of this lab is to figure out what happens when we add more light bulbs to a series or a parallel circuit. Do they become dimmer? Do they become brighter? What happens tot he battery? If we can understand this, then later on we can use light bulbs and/or resistors to control what happens in our circuits.

### Materials

• Two Batteries
• Four identical light bulbs
• Lots of wires
• It works best if you turn the lights off!

### Part 1: Adding Light Bulbs in Series

1. Begin by connecting the two batteries to a single light bulb.
2. Add a another light bulb in series. What happens to the first bulb?
3. Make a prediction: What do you think will happen if you continue to add light bulbs in series?
4. Add three, and then four light bulbs in series.

To understand this lab correctly, they must be identical, otherwise you will see effects that are more difficult to understand.
What happened? Did it match your prediction?
5. Think of a way that you can make light bulbs shut off just by adding more light bulbs. Explain your reasoning. Then, because you have as many light bulbs as you want at the click of a button, try it.

### Part 2: Adding Light Bulbs in Parallel

1. Begin by connecting the two batteries to a single light bulb.
2. Add another light bulb in parallel. What happens to the first bulb?
3. Make a prediction: What do you think will happen if you continue to add light bulbs in parallel?
4. Add three, and then four light bulbs in parallel.

To understand this lab correctly, they must be identical, otherwise you will see effects that are more difficult to understand. What happened? Did it match your prediction?
5. Unlike in series, adding more light bulbs in parallel does not make them dimmer. However, there is a cost to everything! What do you think the "price" is of adding more light bulbs in parallel?