Basic principle of Doppler effect

The basic principle of Doppler effect

1. Basic knowledge of

• Waves are classified by nature ：

• Electromagnetic spectrum
  

• Definition 、 The formula

  frequency ： Number of periodic changes completed in unit time ,$f$ (Hz)

  wavelength ： The distance a wave travels in a vibration period ,$\lambda$ (m)

  Speed ： Wave source velocity $v_s$, Sound wave velocity $u$, Observer speed $v$ (m/s)

  cycle ： Time to complete a cycle change ,$T$ (s)

  The formula 1：
  $$v=f\times \lambda$$
  The formula 2：
  $$T\times f=1$$

2. Derivation of Doppler frequency shift relation