Which term describes the device that detects changes in physical conditions such as light, temperature or pressure?

• A. Input
• B. Sensor
• C. Output
• D. Process

Answer: (B)

A sensor is the device that detects changes in physical conditions such as light, temperature, or pressure and usually converts that change into a signal that a system can use. This ability to sense and translate environmental conditions into measurable data is what lets controllers make decisions and drive actions. For example, a light sensor in automatic lighting detects ambient light levels and informs the system when to switch the lights on or off; a temperature sensor in a thermostat reads room temperature to regulate heating or cooling; a pressure sensor in a tire monitor detects air pressure to warn you if it’s low. This distinguishes a sensor from other concepts: input is any data entering a system, output is what the system produces in response, and a process is the set of operations that transform inputs into outputs.