What describes the frequency shift of a wave relative to a moving observer? By Rabia Anum ✅ Fact Checked 📊 Difficulty Medium 📅 Last Updated 13 Aug 2026 A. Refraction B. Heisenberg Principle C. Doppler Effect D. Photoelectric Effect Check Answer 💡 Explanation: The Doppler Effect explains the change in pitch (frequency) of a sound as its source moves past an observer. 📚 Topics: Physics Science 🎯 Exams: CSS GEN NTS PMS