Which of the following is an example of an INPUT?

• A. Motor coil
• B. Pressure switch
• C. Red pilot light
• D. Auxiliary contact

Answer: (B)

In control circuits, inputs are devices that feed information into the controller so it can make decisions. A pressure switch acts as a sensing element: it monitors a process condition (pressure) and changes its contact state to send a signal to the controller when the set point is reached. That makes it an input.

The other options are actuators or indicators. A motor coil is a load that the controller energizes to drive the motor. A red pilot light is an indicator showing status, not sensing anything. An auxiliary contact is a relay’s contact used to change the circuit or provide interlocking; it’s a switching element within the control path, not a sensor providing a process signal.