(EducationCommonsRW's channel)   Physics - Waves in the Real World: Huygen's Principle Physics - Waves in the Real World: Interference Physics - Waves in the Real World: Introducing the Doppler Effect Physics - Waves in the Real World: Properties of 3D Waves Physics - Waves in the Real World: Shockwaves Physics - Waves in the Real World: Using the Doppler Effect