Question

You have a motion security light by your door cat runs across the in the light turns on what is the input of the system and what is the output

Answer 1

A motion security line is a system that is used to detect motion.
The input for the system is MOTION and the output is LIGHT. That is, when the system detects motion it switch on light.
Remember, an Input is the information that was inserted into a system while the output is the result of the processed information.