This simulation gives you an excellent way to see whether you completely understand the ideas of resistors in series and parallel. Make sure you predict what will happen before turning the circuit on. Were all your predictions correct?
1. With the switch open, what did you predict about bulb C? Why does bulb C do this when the switch is open?
2. With the switch open, which bulb is brighter, bulb A or bulb B? Why is this? Which bulb, A or B, has more current through it?
3. When the switch is closed, what happens to bulb B? Why?
4. With the switch closed, how do bulbs B and C compare? Why?
5. When the switch is closed, what happens to the brightness of bulb A? How can you explain this? One thing to think about is what happens to the overall resistance in the circuit when the switch is closed.