The Doppler frequency shift is the difference between which two frequencies?

The Doppler frequency shift is the difference between which two frequencies?

• A. Phase shift
• B. Beat frequency
• C. Frequency modulation
• D. Transmitted and received frequencies

Answer: (D)

The Doppler frequency shift comes from the fact that motion changes the frequency you actually receive compared to what the source emits. It is the difference between the transmitted (emitted) frequency and the received (observed) frequency. When the source and observer move toward each other, the received frequency is higher; when they move apart, it’s lower. This isn’t about how the wave’s phase changes, nor about a beat between two close frequencies, nor about intentionally modulating the frequency. It’s specifically the gap between what is sent and what is received due to relative motion.

The Doppler frequency shift comes from the fact that motion changes the frequency you actually receive compared to what the source emits. It is the difference between the transmitted (emitted) frequency and the received (observed) frequency. When the source and observer move toward each other, the received frequency is higher; when they move apart, it’s lower. This isn’t about how the wave’s phase changes, nor about a beat between two close frequencies, nor about intentionally modulating the frequency. It’s specifically the gap between what is sent and what is received due to relative motion.