What type of noise is characterized by the movement of electrons in a system?

The correct choice is associated with the random movement of electrons, which is largely responsible for what is referred to as thermal noise or Johnson-Nyquist noise. This type of noise occurs due to the natural thermal agitation of electrons within a conductor, even when no external voltage is applied. As temperature increases, the motion of the electrons becomes more erratic, leading to fluctuations in voltage over time.

Random noise is typically characterized by its unpredictable nature, resulting from these tiny variations in the flow of electric current due to the chaotic motion of electrons. It affects all electronic devices to some extent and can impact the quality of signals in communication systems. Since its characteristics do not exhibit a specific pattern and can vary widely over time, this noise is best classified as random.

Understanding this concept is crucial for working with electronic systems, as distinguishing between types of noise can influence how engineers design circuits to mitigate such interference.