Series Switch AND - Electricity and Electronic Circuits Step by Step

Series switch logic turns an AND rule into a path test: current reaches the lamp only when every switch in the one route is closed. The table is exact for ideal open and closed switch states; real contacts or transistor switches add resistance, leakage, timing differences, uncertain thresholds, and load limits.

Series switches behave like AND because one open switch breaks the only path. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Series switches share one path

In a series network, every switch on the path must be closed before the lamp has a conducting route.

\text{series path} \Rightarrow \text{all switches must close}

One open switch makes off

One switch is closed and the other is open, so the lamp is off.

\text{closed AND open} \Rightarrow \text{off}

Both closed makes on

When both switches are closed, the graph has a complete path and the lamp is on.

\text{closed AND closed} \Rightarrow \text{on}

Only one series row turns on

The full table has four graph states. Any open switch breaks the only path; only both closed turns the lamp on.

\begin{array}{c|c|c}A&B&\text{lamp}\\\text{open}&\text{open}&\text{off}\\\text{open}&\text{closed}&\text{off}\\\text{closed}&\text{open}&\text{off}\\\text{closed}&\text{closed}&\text{on}\end{array}