What does the Doppler effect measure in the context of radar technology?

The Doppler effect, in the context of radar technology, measures changes in frequency as the target moves relative to the radar system. This phenomenon occurs because when a moving object approaches the radar source, the waves emitted by the radar compress, resulting in a higher frequency. Conversely, as the object moves away, the waves are stretched, leading to a lower frequency.

This change in frequency is crucial for speed detection, as it allows the radar system to calculate the speed of the object based on the difference between the transmitted frequency and the received frequency. By accurately measuring these frequency shifts, law enforcement and other organizations can determine how fast a vehicle is traveling.

The other options do not align with the Doppler effect's principles in radar technology. Changes in color of vehicles do not relate to frequency changes, and while changes in sound waves are a general application of the Doppler effect, they are not specifically relevant in radar contexts. Additionally, changes in temperature have no connection to the Doppler effect as it pertains to measuring speed with radar.