Which statement about the coil of a relay is false?

Which statement about the coil of a relay is false?

• A. It is energized by applying voltage across its terminals
• B. It is an output device
• C. It can be used to switch contacts
• D. It is an input device

Answer: (D)

A relay coil acts as an actuator in a control circuit. When voltage is applied across its terminals, it energizes and creates a magnetic field that moves the relay’s contacts, allowing the control signal to switch a load circuit. It doesn’t generate or sense a signal itself—that role belongs to input devices like switches or sensors—so the coil is not an input device. The coil being energized by voltage and its function to switch contacts both describe how it works, making the statement that it is an input device the false one.

A relay coil acts as an actuator in a control circuit. When voltage is applied across its terminals, it energizes and creates a magnetic field that moves the relay’s contacts, allowing the control signal to switch a load circuit. It doesn’t generate or sense a signal itself—that role belongs to input devices like switches or sensors—so the coil is not an input device. The coil being energized by voltage and its function to switch contacts both describe how it works, making the statement that it is an input device the false one.