Q: Two closed-end pipes, when sounded together produce 5 beats/s. If their lengths are in the ratio 100:101, then fundamental notes (in Hz) produced by them are
(a) 245, 250
(b) 250, 255
(c) 495, 500
(d) 500, 505
Ans: (d)
Sol: Frequency $ \displaystyle f \propto \frac{1}{L}$
$\displaystyle \frac{f_1}{f_2} = \frac{L_2}{L_1} $
$ \displaystyle \frac{f_1}{f_2} = \frac{101}{100} $ ..(i)
As , $ \displaystyle f_1 – f_2 = 5 $ …(ii)
Solve (i) & (ii)