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Lighting Light Bulbs

In this activity, students will experiment with batteries and light bulbs to learn about series and parallel circuits.

There are 2 different types of circuits:

  1. Series circuits 

There is only one path from the source through all of the loads (resistance) and back to the source. In other words, all of the bulbs are on the same loop. Each light added in series makes all of the others dimmer, since each light bulb slows down the flow of current. A broken light will interrupt the whole circuit. 

  1. Parallel circuits

Every load (resistance) is connected in a separate path and receives the full circuit voltage. In other words, each bulb is connected on a separate loop to the energy source. Two lights connected in a parallel circuit will be as bright as one by itself. The drawback is that the energy source gets drained quickly.

Objectives

  • Demonstrate the different ways to complete a circuit (parallel or series).

Materials

  • Per Class:
    wire cutters
    wire strippers

  • Per pair of students:
    1 D-cell battery
    four 10 cm lengths of insulated wire
    2 light bulbs (with a rating of no more than 2 volts each)
    Electric Circuits Worksheet (one per student)

Key Questions

  • Part 1: Light the bulbIn how many different ways can you light the bulb?
  • Which of the configurations on the worksheet had you already tried?
  • What is the same about all the circuits that light up the bulb?
  • How about all the circuits that don’t light up the bulb?
  • What other materials could we use instead of wires?
  • Part 2: Light the bulb Why are the bulbs in Circuit A glowing dimly?
  • Why are the bulbs in Circuit B glowing brightly?
  • When you remove one of the bulbs from its holder in Circuit A, why does the other bulb turn off?
  • What type of circuit do you think we have in our homes?
  • In Circuit B, why does the second bulb stay on?
  • How are decorative lights (like Christmas tree lights) connected?

What To Do

Preparation

  1. Cut enough lengths of insulated wire for the class.
  2. Strip both ends of every wire.
  3. Gather together sets of materials, one for each group.

Exploration

  1. Divide students into groups of 2 or 3.
  2. Provide each group with one battery, one bulb and one wire.

Part 1: Light the bulb 

  1. Challenge the students to light the bulb using only the battery and 1 wire.
  2. As students find ways to light their bulbs, have them draw their configuration.
  3. Add a second wire and test more ways to light the bulb.

Part 2: Dimmer and brighter 

  1. Give each group two mini-lights, two wires, and a pair of batteries. Tape the batteries together (it may be convenient to tape the batteries to the table or to a paper plate.
  2. Set up Circuit A and observe the bulbs.
  3. Remove one of the bulbs from its socket and see what happens.
  4. Set up Circuit B and observe the bulbs. Compare your findings with Circuit A.
  5. Remove one of the bulbs from its socket and see what happens.
  6. Option: Hand out the Electirical Circuit Worksheet.

Extensions

  • Provide more bulbs and lengths of wire to compare longer series and parallel circuits.
  • Join the class together to create a giant series and a giant parallel circuit!
  • Try and light a standard household bulb. You may have to use all the batteries in the class lined up together!
  • Provide students with different examples of everyday circuits e.g. Christmas lights, lamps, power bars etc. and investigate whether they are in series, parallel or a combination.

Other Resources

BC Hydro | Exploring Simple Circuits

BC Hydro | Exploring Series and Parallel Circuits

BC Hydro | Electrical Safety