A sound source that moves in relation to you, then its sound pitch changes. This sound effect establishes that the source of sound is moving towards or away from you and you can also estimate its speed, this effect is called as Doppler effect.
It can be further described as an effect that is produced by an object generating sound waves while moving, which are upward frequency towards whom the object is approaching. In the same way, the frequency of the sound waves is in downwards for observers from whom the object is moving away.
The doppler effect is not only with the sound waves, but it can also be found in the water wave, light wave and much more. However, we are familiar with the effect produced by sound waves. For instance siren from an ambulance and police vehicle. As the vehicle approaches towards you the pitch and frequency are higher, while it is inverse when moving away from you.
- A tennis ball.
- Battery and connector.
- A strong string.
- Rubber bands.
- Scrap paper.
- Cut the ball into 2 halves with a knife.
- Connect the battery, switch and the buzzer. Battery and buzzer should have terminals – positive and negative. Make sure to connect the matching terminals. Now to the one wire attach the switch.
- Place both the battery and buzzer along with the connected wire inside the ball. Leave the switch outside the ball and adjust it to fix on the edge of the ball.
- With the scrap papers, pack the ball loosely. Ensure that the buzzer is close to the outside edge.
- Close the ball and use the rubber band to pack it thoroughly.
- Use tape to fix the switch on the ball.
- Attach the strong string on the ball and tape it securely.
- Now the doppler effect project is ready.
Switch on buzzer and string, now twirl the ball around your head. You will observe the frequency of a sound wave. Notice how the pitch of the buzzer changes as the ball approaches you and move away from you. Well, with this experiment you have experienced the doppler effect. Have you examined the shift in sound wave frequency produced by a moving source?