Free electrons in the sensor produce what?

• A. Electric potential
• B. Magnetic field
• C. Light
• D. Heat

Answer: (A)

Free charges set up an electric potential difference. When electrons move or redistribute in a sensor, they create a voltage between points (electrodes) that the sensor can measure. That electrical potential is the primary signal produced by the presence of free electrons in this context. Magnetic fields would come from current flow, but the typical output in this scenario is the voltage. Light and heat aren’t inherent outputs just from having free electrons unless specific processes (like emission or resistive heating) occur, which aren’t the default signal here.