How are switches wired to form an AND logic circuit?

• A. Normally opened in series
• B. Normally closed in parallel
• C. Normally opened in series with a normally closed
• D. Normally opened in parallel

Answer: (A)

Two-input AND logic means both conditions must be true for the output to be active. In a switch network, that’s achieved by placing normally opened switches in series. Each normally opened switch is closed only when its input is activated, so the electrical path exists only if both switches are closed. If either switch remains open, the circuit is interrupted and the output stays off, reflecting the AND condition. Parallel arrangements produce OR behavior, where any closed path allows current, and using a normally closed element changes the default state and does not give a straightforward two-input AND.