Tuning fork F1 has a frequency of 256 Hz and it is observed to produce 6 beats/second with another tuning fork  F2. When F2 is loaded with wax, it still produces 6 beats/second with F1. The frequency of  F2 before loading was

nA = Known frequency = 256 Hz, nB = ?x = 6 bps, which remains the same after loading.Unknown tuning fork F2 is loaded so nB↓Hence nA – nB↓  = x        ... (i)         →         Wrong            nB↓  – nA = x        ... (ii)        →        Correct⇒ nB = nA + x = 256 + 6 = 262 Hz.