Lights, Sound, Action

Time: 30-45 minutes

Materials

Wire Cutter or Needle-nose pliers / Wire stripper or knife / D-cell batteries / Flashlight bulbs
Insulated copper wire (12-15 cm/ 5-6 in long) / Bulb holders / Buzzer / Motor and fan blade
Masking or transparent tape / 4 alligator clips / Flashlight

Note: Don’t leave circuits connected for too long. They will overheat.

Directions

  1. Distribute three batteries, two bulbs and bulb holders, five pieces of wire, tape, and four alligator clips to each pair of students.
  2. Instruct the students to gently screw one bulb into a bulb holder. Using two of the wires, they should connect one end of each wire to each of the two clips on the bulb holder.
  3. Tell them to connect the loose end of one of the wires to one end of the battery and secure them with tape if needed. Then, connect the loose end of the other wire to the other end of the battery.
  4. Encourage the students to experiment with different combinations of connections between the bulb and the battery. For example, have them find out what happens when they connect both wires to the same end of the battery (the bulb won’t light). Remind students that when the bulbs light, they have made a complete (closed) circuit. If the path is broken or interrupted anywhere along the path, the circuit will not be complete, the current will not flow, and the bulb will not light.
  5. Challenge the students to light two bulbs at the same time. They may use an additional battery in their circuit. Tell them that when a circuit is wired so that the electricity flows first through one bulb and then trough a second bulb, we say that the circuit is wired in series. Have them notice what happens to the brightness of the first bulb when a second is added in the circuit and what happens when a second battery is added.
  6. Have the students unscrew one of the bulbs in their series circuit to find out what happens (neither bulb will light because the circuit has been interrupted at the point where one of the bulbs is disconnected).
  7. Direct the students to give each bulb its own circuit. Ask them if both bulbs light. If so, are they brighter, dimmer, or the same as in the series circuit? Remind them that when a circuit is wired to give each bulb its own circuit, we say that it is wired in parallel. The current can flow to each bulb at the same time, rather than one after the other.
  8. Have the students disconnect one of the bulbs in their parallel circuit and ask them what happens to the other bulb (the connected bulb will stay lit).
  9. Have the students explore different arrangements of wires, batteries, and buzzer to make the buzzer sound.
  10. Tell them to gently push the fan blade onto the shaft of the electric motor. Have them experiment with various connections among the batteries, wires, and motor to make the fan blade move.

If Time Allows

  1. Let the students work in groups of four or more and challenge them to combine their materials to build super circuits. For example, they might build a circuit that:
  2. Lights the most bulbs at the same time using the fewest number of batteries
  3. Is the longest circuit
  4. Lights the most bulbs simultaneously using the fewest pieces of wire
  5. Have the students construct a circuit that produces light, sound, and motion all at once using the bulb(s), buzzer, fan motor, wires, and batteries.
  6. Have the students take apart some flashlights to trace the circuit’s path. The current flows from the terminal of one of the batteries to the metal strip lining the inside wall of the flashlight body. The metal strip connects to the base of a socket, which has metal pieces that pass through the socket to where the metal part of the bulb attaches. The current flows through the socket along that metal piece to the base of the bulb and then into the filament. The current flows through the filament, causing it to glow, and then out the other side into the base of the bulb and back along the metal piece through the socket and to the metal strip or tab that connects to the positive end of the battery. Locate the place along this circuit where the switch completes the connection that allows the current to flow.

Discussion

  • Why do batteries die?
  • After a while, the chemical reactions inside the battery that cause electrons to move away from atoms, leaving those atoms positively charged, no longer occur. This is when the chemicals in the battery get used up and there is no more charge build-up at the battery terminals.
  • What does the number of volts on a battery mean?
  • The voltage on the battery indicates the amount of electrical potential of the battery. Batteries such as A, AA, C, and D carry 1.5 volts. Additional voltage can be obtained by connecting multiple batteries together.
  • Why are batteries different sizes?
  • Larger batteries contain more chemicals than small batteries. More chemical reactions can occur in large batteries which means that more current can be produced from the battery. So, larger batteries can keep the chemical reactions going fast enough longer to keep up with the demand for current that some devices require in order to work.