When a tuning fork A of unknown frequency is sounded with another tuning fork B of frequency 256 Hz, then 3 beats per second are observed. After that A is loaded with wax and sounded, the again 3 beats per second are observed. The frequency of the tuning fork A is

It is given that nA = Unknown frequency = ?nB = Known frequency = 256 Hzx = 3 bps, which remains same after loading Unknown tuning fork A is loaded so nA↓Hence nA↓ – nB  = x        ... (i)        →       Correct            nB  – nA↓ = x        ... (ii)       →        Wrong⇒ nA = nB + x = 256 + 3 = 259 Hz.