A tuning fork of frequency 480 Hz produces 10 beats per second when sounded with a vibrating sonometer string. What must have been the frequency of the string if a slight increase in tension produces lesser beats per second than before

If suppose nS = frequency of string =12lTmnf = Frequency of tuning fork = 480 Hz x = Beats heard per second = 10as tension T increases, so nS increases (↑)Also it is given that number of beats per sec decreases (i.e. x↓)Hence nS↑ – nf  = x↓        ... (i)          →      Wrong            nf  – nS↑ = x↓        ... (ii)         →      Correct⇒ nS = nf – x = 480 – 10 = 470 Hz.