Doppler effect

Episode of Series “College Physics”. Explains the factors which determine the pitch of a sound. Waves are shown advancing toward the listener, and the following cases are treated: 1. Source and listener stationary; 2. Source in motion, listener stationary (accompanying change of wave-length and consequent change of apparent frequency are described in slow motion); 3. Source stationary, listener in motion (shows that no change in wave-length occurs, but that there is a change of apparent frequency).