PCS 125 Lecture 19: PCS 125 Lecture 19
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The speed of the sound is v, the frequency is , and the wavelength is l. When the observer moves toward the source, the speed of the waves relative to the observer is v " = v + vo. The frequency heard by the observer, ", appears higher when the observer approaches the source. The frequency heard by the observer, ", appears lower when the observer moves away from the source. Consider the source being in motion while the observer is at rest. As the source moves toward the observer, the wavelength appears shorter. As the source moves away, the wavelength appears longer. When the source is moving toward the observer, the apparent frequency is higher. When the source is moving away from the observer, the apparent frequency is lower. Combining the motions of the observer and the source. The signs depend on the direction of the velocity.
