an ambulance is approaching a stationary observer. for the observer, the apparent frequency of the siren compared to the actual frequency of the siren

Answer 1

The apparent frequency of the siren as heard by the stationary observer will be higher than the actual frequency of the siren. This effect is known as the Doppler effect and occurs when there is relative motion between the observer and the source of sound.

When the ambulance approaches the observer, the sound waves from the siren get compressed, causing an increase in perceived frequency. As a result, the apparent frequency of the siren will be higher than its actual frequency. This is often described as a higher pitch sound.

Conversely, when the ambulance is moving away from the observer, the sound waves get stretched, causing a decrease in perceived frequency. In this case, the apparent frequency of the siren will be lower than its actual frequency, leading to a lower pitch sound.

It is important to note that the actual frequency of the siren remains constant. It is only the perceived frequency that changes for the observer due to the relative motion between the observer and the source of sound.