Changes

This is commonly experienced in the passing of a train where a bystander hears the pitch of the whistle change as it passes sounding like '''''deee-daah'''''.

This is commonly experienced in the passing of a train where a bystander hears the pitch of the whistle change as it passes sounding like '''''deee-daah'''''.

In the case of light, when the observer and light source approach each other, the the wavelength of the light decreases, shifting the observed light to the blue end of the [[spectrum]], known as a blue shift.  Conversely, when the observer and light source move away from each other, the light shifts to the red end of the spectrum, known as a [[red shift]].    

In the case of light, when the observer and light source approach each other, the the wavelength of the light decreases, shifting the observed light to the blue end of the [[spectrum]], known as a blue shift.  Conversely, when the observer and light source move away from each other, the light shifts to the red end of the spectrum, known as a [[red shift]].  

The effect was named after Austrian [[Christian Johann Doppler]], who provided the first technical explanation of the phenomenon in 1842.

The effect was named after Austrian [[Christian Johann Doppler]], who provided the first technical explanation of the phenomenon in 1842.

[[Category:Physics]]

[[Category:Physics]]