The key to understanding the Doppler effect lies in constructing a dynamic "wave source motion picture" in your mind. If the wave source is stationary, the waves it emits spread outwards like concentric circles centered on it. Once the wave source begins to move, this picture is completely changed: the wave source continuously emits new waves as it moves. Because its position at each emission point is different, waves in front of it in the direction of motion are "compressed" together (high frequency), while waves behind it are "stretched" apart (low frequency). This visual effect of "compression" and "stretching," when demonstrated using visible wave forms such as water ripples and light patterns, becomes exceptionally intuitive and impactful, allowing one to grasp its core idea more instantly than any formula. Our "Doppler Effect" exhibit is precisely such a dynamic theater that perfectly visualizes this abstract picture. You press a button to start the device. The core oscillator b
