Which device can switch several circuit paths from a single coil activation?

Which device can switch several circuit paths from a single coil activation?

• A. Two-way switch
• B. Resistor (nonvariable)
• C. Dual on/off switch
• D. Relay (relay switch)

Answer: (D)

This is about an electromechanical switch that can control several circuits at once using one small coil. A relay uses a magnetic coil; when you energize that coil, the magnetic field pulls a movable contact to a new position. That movement can affect multiple contact sets that are all tied to the same actuator, so several circuit paths switch states together from a single coil activation. In other words, one coil can control multiple poles (like two, three, or more contacts) at the same time, providing isolation between a low-power control circuit and the higher-power load circuits. The other options don’t fit this behavior. A manually operated two-way switch is operated by hand and doesn’t rely on a coil to drive multiple paths. A nonvariable resistor is just a passive element that does not switch paths at all. A dual on/off switch handles two circuits manually; it isn’t activated by a coil to switch multiple paths simultaneously.

This is about an electromechanical switch that can control several circuits at once using one small coil. A relay uses a magnetic coil; when you energize that coil, the magnetic field pulls a movable contact to a new position. That movement can affect multiple contact sets that are all tied to the same actuator, so several circuit paths switch states together from a single coil activation. In other words, one coil can control multiple poles (like two, three, or more contacts) at the same time, providing isolation between a low-power control circuit and the higher-power load circuits.

The other options don’t fit this behavior. A manually operated two-way switch is operated by hand and doesn’t rely on a coil to drive multiple paths. A nonvariable resistor is just a passive element that does not switch paths at all. A dual on/off switch handles two circuits manually; it isn’t activated by a coil to switch multiple paths simultaneously.