Define 'thermal noise' in radio communications.

Thermal noise, also known as Johnson-Nyquist noise, is defined as noise generated by the random motion of electrons within a conductor or semiconductor. This phenomenon occurs due to the thermal energy present in the material at a given temperature, which causes the free electrons to move unpredictably. As these electrons move, they generate voltage fluctuations that manifest as noise in the signal being transmitted or received.

In radio communications, thermal noise is important to consider because it contributes to the overall noise floor in a communication system, affecting the clarity and quality of the received signal. Since thermal noise is inherent to electronic components and is influenced by temperature, it cannot be eliminated entirely but can be minimized through careful design and selection of components. The understanding and management of thermal noise are crucial for optimizing the performance of radio communication systems.