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(i) What is the principle on which sonar is based? (ii) Calculate the minimum distance at which a person should stand in front of a reflecting surface so that he can hear a distinct echo. (Take speed of sound in air = 350ms-1.) |
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Answer» 1. Sonar is based on echo. 2. The sensation of sound persists in our ears for about 1/10th, of a second after exciting stimulus ceases to act. If d is the distance between the observer and obstancle and v the speed of sound, the time taken to hear the echo is t = Distance travelled in going and coming back/speed of Sound of v = 340 ms-1 ∴ Minimum distance of 17.5m from the listner, to hear. echo distinctly. |
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