Christian Doppler discovered what we now call the "Doppler Effect" by measuring:
A) the wavelengths of the Balmer lines of hydrogen
B) the intensity of the red and blue light from the same star
C) the changes in the radar gun used by his local police officers when they pointed at speeding cars
D) the changes in the colors of a rainbow when the clouds were moving fast
E) the properties of sound waves coming from a group of musicians on a moving, open railroad car

Question

Quizplus · Accepted Answer

Christian Doppler discovered the Doppler Effect by studying the properties of sound waves coming from a group of musicians on a moving, open railroad car. He noticed that as the train approached a stationary listener, the pitch of the sound waves increased, while as the train moved away from the listener, the pitch decreased. This led him to the discovery of the Doppler Effect, which describes the shift in frequency and wavelength of waves (sound, light, or radio waves) due to the motion of the source or observer.

Christian Doppler Discovered What We Now Call the "Doppler Effect