______ Relays are used where it is necessary for the contact state to stay open or closed even if the coil is energized only momentarily.

• A. Latch
• B. Momentary
• C. Magnetic
• D. Reed

Answer: (A)

Latching relays are designed to remember their last contact state after the coil is energized only briefly. They are bistable devices: a short pulse can set the contacts to open or closed, and the state remains there even when the coil power is removed. To change the state again, another pulse is required—either with a second coil (set and reset) or with a single coil that toggles using a different signal. This tendency to hold its state makes latch relays ideal for memory-like functions and for saving power, since you don’t need continuous coil energization to maintain the contact position.