SWITCHES

1. What is the effect on the bulbs when the various switches are turned on or off?

    (a) When the switches in a series and a parallel circuits are closed,
          the bulbs light up because the circuit are complete.

Series circuit

Parallel circuit

    (b) If a series circuit has more than one switch, all the bulbs do not light up
          if any one switch is open.

When switch P is closed and switch Q is open, bulbs R and S do not light up.

When switch P is open and switch Q is closed, bulbs R and S do not light up.

    (c) In a parallel circuit, each bulb is connected to its own switch.
         When one of the switches is open, only  the bulb connected to
         this switch will not light up. The other bulbs will still light up.

When switch W is closed and switch X is open, bulb Y lights up and bulb Z does not light up.

When switch W is open and switch X is closed, bulb Y does not light up and bulb Z lights up.