What is the Doppler Principle in the context of RADAR?

The Doppler Principle in the context of RADAR pertains to how the frequency of waves changes in relation to the relative motion between the source of the waves and an observer or an object. When a RADAR system emits waves towards a moving object, the waves are reflected back to the receiver. If the object is moving towards the RADAR, the frequency of the reflected waves increases, and if the object is moving away, the frequency decreases. This change in frequency is what allows the RADAR system to determine the speed of the object.

The correct answer highlights that the number of reflected waves per second changes with the object's speed relative to the RADAR system, which is fundamental to how Doppler RADAR works. This frequency shift is directly proportional to the speed of the object, enabling law enforcement and other entities to accurately measure speed.

In contrast, other options do not correctly capture the essential aspects of the Doppler Principle as it applies to RADAR technology. The speed of light being constant is indeed true, but it is not specific to the understanding of the Doppler effect. The idea that frequency can only be measured in stationary objects is fundamentally incorrect, as frequency can be measured in moving objects through the Doppler effect. Lastly, the notion that