Question

Two closed organ pipes, when sounded together give five beats per second. Their lengths are in the ratio of 100 : 101. The fundamental notes (in Hz.) produced by them are

• A. 245, 250
• B. 250, 255
• C. 495, 500
• D. 500, 505

Answer 1

Answer: (D)

500, 505

Answer is D.
The ratio of the lengths of the closed organ pipes is equal to the fundamental notes produced by them.
That is, $L_1/L_2=f_1/f_2$, since $L_1/L_2=100/101$
So in (option D) we have $f_1/f_2=500/505=100/101$.
Hence, the fundamental notes (in Hz.) produced by them are 500, 501.