स्टेथोस्कोप ध्वनि के किस सिद्धान्त पर कार्य करता है ? - On which principle of sound does the stethoscope work? - Stethoscope Dhwani Ke Kis Sidhhant Par Karya Karta Hai ? General Science in hindi, Physics Apvartan question answers in hindi pdf Vivartan questions in hindi, Know About Paravartan General Science online test General Science notes in hindi quiz book Dhruvan
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Reflection of sound
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