Genius Maker - School software - Physics software DOPPLER EFFECT

Features:

The Doppler effect is a acoustic physics software, which facilitates to find out the frequency of sound observed by a stationery observer from a moving source of sound. A typical sound is also played in the background. This software module is basically built for students to understand how the observed frequency changes when the source of sound is moving.

How to start with Doppler Effect software ?

• Open Genius Maker software and click "Doppler effect" button. It opens the Doppler effect window.
• On opening you will see that default values are entered for velocity of the car and Horn frequency.
• You may change the velocity either by directly entering the value in the box are by moving the slider.
• Just click "Start & Sound horn" button.
• You will notice that the car starts moving and sound waves coming from the car.
• When the sound wave reaches the observer (ie., signal light), a sound is also played, representing a typical approaching horn sound. The value of observed horn frequency is also displayed beneath the signal light.
• When the car crosses the observer, the value of observed frequency changes and the sound also changes to different one, representing a typical receding horn sound. 

• If you want to turn off sound, click "Switch - off sound". You cannot turn this switch on, while the car is moving.
• The "Pause" and "Stop" buttons are applicable for the car movement.
• Let us solve a few sample physics problems involving Doppler effect by using this software.

EXAMPLE - 1

• A car is approaching an observer with a speed of  30 m/s and the frequency of its horn is 650 Hz. What is the frequency of the horn observed by the observer ?

• Enter the following values in the vehicle parameters box.

  • Car velocity = 30 m/s
  • Horn Frequency = 650 Hz

• Click "Start & Sound horn" button.

• You will notice that the car starts moving and sound waves coming from the car.
• When the sound wave reaches the observer (ie., signal light), the value of observed horn frequency is displayed beneath the signal light.

• It displays the value as 712.9 Hz

• Hence the answer to the current question is 712.9 Hz

EXAMPLE - 2

• A train is receding from an observer with a speed of  40 m/s and the frequency of its horn is 722 Hz. What is the frequency of the horn observed by the observer ?

• Enter the following values in the vehicle parameters box.

  • Car velocity = 40 m/s
  • Horn Frequency = 722 Hz

• Click "Start & Sound horn" button.

• You will notice that the car starts moving and sound waves coming from the car.
• When the sound wave reaches the observer (ie., signal light), the value of observed horn frequency is displayed beneath the signal light. It is displayed as 818.27 Hz
• Wait for the car to move past the observer (signal light). Since the current question is pertaining to the receding vehicle.
• When the car moves past the signal light, the observed frequency changes to 646 Hz.

• Hence the answer to the current question is 646 Hz

What is sonic boom ?

• To understand the phenomena of sonic boom, enter Car velocity = 340 m/s. 

• Click "Start & Sound horn" button.

• You will notice that the car starts moving and sound waves coming from the car. In the forward direction, the new waves generated are traveling along with the old waves. It is because, the car travels at a speed near to that of sound itself.
• The sound wave reaches the observer along with the car. At that time you can witness a sonic boom.

Warning Note

• This software module is intended for explaining the Doppler effect phenomena in sounds. A car movement is used to explain this phenomena. It should be noted by the students that, in reality no vehicle on the ground can move with such high velocities.