WGU RNT2 Task 3 | Passed on First Attempt |Latest
Update with Complete Solution
A. The Doppler Effect
The Doppler effect is the change in the frequency of a wave that happens when there is motion
between the source of the wave and the observer. Named after the Austrian scientist Christian
Doppler, who first described it in the 1800s, we notice this effect in everyday life more often
than we realize. For example, when an ambulance drives toward a person, the siren sounds
higher, but the pitch drops once it passes and moves away. The siren itself never changes its
sound. What changes is how the motion affects the way we receive the sound waves (Hewitt,
2015).
A1. What is the effect
In physics, waves carry energy from one place to another. The frequency of a wave tells us how
many crests pass a certain point in a given amount of time, and the wavelength is the distance
between one crest and the next. When the source of a wave and the observer are both still, the
observer hears or sees the wave at its actual frequency. However, when one of them moves,
the spacing of the waves changes. If they move toward each other, the crests arrive more often,
and the frequency appears higher. If they move apart, the crests arrive less often, and the
frequency seems lower (Hewitt, 2015).
A2. Why the Doppler Effect Occurs
The Doppler effect happens because motion causes waves to compress or spread out. When a
wave source moves toward an observer, each new wave crest begins closer to the observer
than the one before it. This shortens the wavelength and increases the frequency. If the source
moves away, each wave starts from farther away, spreading them out and lowering the
frequency. It does not matter whether the source, the observer, or both are moving—the key is
their motion relative to each other (Hewitt, 2015).
A3. Two Examples of the Doppler Effect
Sound Waves
One of the easiest ways to experience the Doppler effect is through sound. Imagine standing
near a street as an emergency vehicle drives by. When the vehicle approaches, the sound
waves in front of the vehicle are pushed closer together, making the pitch sound higher. The
waves stretch out as they pass and move away, and the pitch sounds lower. The siren produces
Update with Complete Solution
A. The Doppler Effect
The Doppler effect is the change in the frequency of a wave that happens when there is motion
between the source of the wave and the observer. Named after the Austrian scientist Christian
Doppler, who first described it in the 1800s, we notice this effect in everyday life more often
than we realize. For example, when an ambulance drives toward a person, the siren sounds
higher, but the pitch drops once it passes and moves away. The siren itself never changes its
sound. What changes is how the motion affects the way we receive the sound waves (Hewitt,
2015).
A1. What is the effect
In physics, waves carry energy from one place to another. The frequency of a wave tells us how
many crests pass a certain point in a given amount of time, and the wavelength is the distance
between one crest and the next. When the source of a wave and the observer are both still, the
observer hears or sees the wave at its actual frequency. However, when one of them moves,
the spacing of the waves changes. If they move toward each other, the crests arrive more often,
and the frequency appears higher. If they move apart, the crests arrive less often, and the
frequency seems lower (Hewitt, 2015).
A2. Why the Doppler Effect Occurs
The Doppler effect happens because motion causes waves to compress or spread out. When a
wave source moves toward an observer, each new wave crest begins closer to the observer
than the one before it. This shortens the wavelength and increases the frequency. If the source
moves away, each wave starts from farther away, spreading them out and lowering the
frequency. It does not matter whether the source, the observer, or both are moving—the key is
their motion relative to each other (Hewitt, 2015).
A3. Two Examples of the Doppler Effect
Sound Waves
One of the easiest ways to experience the Doppler effect is through sound. Imagine standing
near a street as an emergency vehicle drives by. When the vehicle approaches, the sound
waves in front of the vehicle are pushed closer together, making the pitch sound higher. The
waves stretch out as they pass and move away, and the pitch sounds lower. The siren produces
