Explain the Doppler effect for sound when the source moves toward the observer.

Explain the Doppler effect for sound when the source moves toward the observer.

• A. The observed frequency increases; f' = f v /(v − v_s) for a moving source toward the observer
• B. The observed frequency decreases.
• C. The observed wavelength increases.
• D. The speed of sound changes.

Answer: (A)