Investigation 17D: Series and parallel circuits

Essential questionsWhat are the advantages and disadvantages of series versus parallel circuits?
Have you ever had a string of holiday lights where one bulb is burned out, preventing all the other bulbs from lighting? Was it easy to find the burned out bulb? This investigation explores series and parallel circuits by connecting bulbs and observing their brightness. By comparing the two circuit types, you will learn why the wiring of some strings of lights allows one bad bulb to disconnect all the other bulbs.
Part 1: Connecting bulbs in series

Part 1: Connecting bulbs in series
  1. Create a circuit using two batteries, one bulb, a switch, and any necessary wire modules.
  2. Close the switch and observe the brightness of the bulb.
  3. Create a circuit with two bulbs in series, as shown in the circuit diagram. Compare the brightness of the two lamps to the previous circuit with one lamp.
  1. What property makes this a series circuit?
  2. How bright are the two bulbs in series compared to a single bulb circuit? Why?
  3. Unscrew one bulb from the series circuit. What happens to the other bulb? Why?
Part 2: Connecting bulbs in parallel

Part 2: Connecting bulbs in parallel
  1. Create a circuit with two bulbs in parallel, as shown in the circuit diagram.
  2. Compare the brightness of the bulbs in this circuit to the prior circuit with two bulbs in series.
  1. What property makes this a parallel circuit?
  2. How bright are the parallel bulbs compared to the series bulbs? Compared to the single bulb? Why?
  3. Unscrew one bulb from the parallel circuit. What happens to the brightness of the other bulb? Why?
  4. Is a series or parallel circuit better for connecting a string of lights? Why?
  5. Design a circuit of three bulbs that combines series and parallel arrangements, and sketch the circuit diagram. Predict the relative bulb brightness based on the previous experiments. Build the circuit and test your predictions. Were you correct?

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