Both the lamp and the switch in Fig 5 circuit are laid out in series.

The total current from the battery must flow through the lamp and switch in series (one after the other). if the switch becomes faulty, the lamp fails or there is a break in the circuit wire there will no current flow through the circuit.

There are two basic ways in which the components of an electric circuit can be connected.

In series, the components are linked in a row so that the total current passes through each one before moving onto the next (see figure 6a).

In a parallel circuit the components are electrically linked in a side by side layout. In this way the total voltage is applied to every branch of the circuit. when you apply a voltage to the circuit the current divides. Each branch of the circuit has a proportion of the current flowing through it. (see Fig 6b).