Saved Bookmarks
| 1. |
19. Two tuning forks A and B produce 5 beats per sec. If fork A is inresonance with a closed organ pipe of length 20 cm and B is inresonance with an open pipe of length 40-5 cm, then calculate theirfrequencies, |
|
Answer» assume that the air column in resonance with fork A is closed at one end and open at one end. Then the second column that is in resonance with fork B is open at both ends. Further we take that the resonance frequencies in question are the fundamental frequencies and not hormonics. Let velocity of sound be = c. Frequency of fork A = f1frequency of fork B = f2 beats = | f1 - f2 | = 4 Hz f1 = resonance frequency of closed Air column 15 cm λ / 4 = 15 cm => λ = 60 cm => f1 = c / 60 Hz f2 = resonance frequency of open air column 30.5 cm λ / 2 = 30.5 cm => λ = 61 cm => f2 = c / 61 Hz f1 - f2 = c * [1/60 - 1/61] = c / 3660 = 4 Hz => c = 14, 640 m/s => f1 = 244 Hz and f2 = 240 Hz |
|