Have you ever tested old batteries in a 2-cell torch? If so, you know that both of the cells need to be working. If one cell has leaked, the torch won’t work. No matter how strong the other cell is, if one cell is bad the light won’t go on. That’s because the electricity needed to light the bulb must flow through both cells. If one cell is dead, the path is blocked. There’s no way around it.
Things Required:
Two “D” cells in battery holders
Two torch bulbs in lamp holders
Switch
Connecting wires with each end stripped 11/2 inches bare of insulation
Directions:
Assemble the setup shown below.
Close the switch. What happens? Do both bulbs light? Is one bulb brighter than the other? In this circuit, how many different paths can the electrons flow through?
Keep the switch closed. Unscrew one of the bulbs. What happens?
Can you explain your observations? Draw a diagram of this circuit using the symbols presented earlier. Use this diagram to describe the flow of electrons.
This Is What Happens:
The circuit you built is called a series circuit. It offers only one path for the moving charges. All the electrons must travel through the same circuit components.
If one of the wires is broken (or one of the components removed), the circuit is opened. All current stops! That’s why the other bulb went out, even though it remained attached to the circuit.
