The Doppler Effect
Doppler Effect
Objectives
* Measure the detector frequency for waves emitted from a slowly moving source as that source is approaching the detector. (Exploration 1) * Calculate the detector frequency for waves emitted from a slowly moving source as that source is moving away from the detector. (Exploration 2) * Sketch the wave-front patterns for wave sources with various source speeds. (Exploration 3)
Description of Activity
In this activity, you will study waves that travel from a moving source to a detector. You will control the source speed as well as the frequency of waves emitted by that source. You will observe the wave fronts and measure the frequency at the detector. The Jump Start exercises below will help you review frequency, wavelength, pitch, and the Doppler effect.
Jump Start 1. What type of wave is a sound wave? A sound wave is a longitudinal waves. 2. Define wave frequency. Wave frequency is the number of crests that pass through at a specified time. 3. What is pitch? A pitch is the sound or sensation of the frequency. 4. Sketch one wavelength of a longitudinal wave.
Exploration 1: A Wave Source Moving Towards a Detector
Procedure
1. Explore the simulation on your own for several minutes. Attempt to identify relationships among source frequency, detector frequency, wave speed, and source velocity. 2. Set Source speed to 1.0 cm/s. Move the detector by dragging it from the left side of the screen onto the grid; place it on the right side of the grid, directly opposite the wave source. Set Wave speed to 5.0 cm/s. Select a Source frequency. Record this frequency in Table 1. 3. The top stopwatch in this Virtual Investigation starts automatically when the first wave front touches the detector. The second stopwatch does not start until the source has passed the detector. Select Go. Using the top stopwatch, observe the number of waves that pass the detector in 1.0 s. This is the detector frequency. Record
Objectives
* Measure the detector frequency for waves emitted from a slowly moving source as that source is approaching the detector. (Exploration 1) * Calculate the detector frequency for waves emitted from a slowly moving source as that source is moving away from the detector. (Exploration 2) * Sketch the wave-front patterns for wave sources with various source speeds. (Exploration 3)
Description of Activity
In this activity, you will study waves that travel from a moving source to a detector. You will control the source speed as well as the frequency of waves emitted by that source. You will observe the wave fronts and measure the frequency at the detector. The Jump Start exercises below will help you review frequency, wavelength, pitch, and the Doppler effect.
Jump Start 1. What type of wave is a sound wave? A sound wave is a longitudinal waves. 2. Define wave frequency. Wave frequency is the number of crests that pass through at a specified time. 3. What is pitch? A pitch is the sound or sensation of the frequency. 4. Sketch one wavelength of a longitudinal wave.
Exploration 1: A Wave Source Moving Towards a Detector
Procedure
1. Explore the simulation on your own for several minutes. Attempt to identify relationships among source frequency, detector frequency, wave speed, and source velocity. 2. Set Source speed to 1.0 cm/s. Move the detector by dragging it from the left side of the screen onto the grid; place it on the right side of the grid, directly opposite the wave source. Set Wave speed to 5.0 cm/s. Select a Source frequency. Record this frequency in Table 1. 3. The top stopwatch in this Virtual Investigation starts automatically when the first wave front touches the detector. The second stopwatch does not start until the source has passed the detector. Select Go. Using the top stopwatch, observe the number of waves that pass the detector in 1.0 s. This is the detector frequency. Record