Parallel Switch OR - Electricity and Electronic Circuits Step by Step

Parallel switch logic turns an OR rule into alternate conducting routes: either closed branch can complete the lamp path. The ledger treats open branches as perfectly open and closed branches as perfectly conducting, while real hardware brings contact resistance, leakage, bounce, delay, threshold spread, and measurement uncertainty.

Parallel switches behave like OR because either branch can complete a 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

Parallel switches offer alternate paths

In a parallel network, either branch can connect the lamp to the source return.

\text{parallel branches} \Rightarrow \text{either path can close}

One closed branch is enough

Close the upper branch while the lower branch stays open. The lamp is on.

\text{closed OR open} \Rightarrow \text{on}

Either branch can do it

Open the upper branch and close the lower branch instead. The lamp is still on.

\text{open OR closed} \Rightarrow \text{on}

Both closed is also on

Closing both branches gives two conducting choices, so the lamp is on.

\text{closed OR closed} \Rightarrow \text{on}

Only both open turns off

The full table has four graph states. Parallel topology turns the lamp on when either branch is closed.

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