Question

If two tuning forks A and B are sounded together, they produce 4 beats per second. A is then slightly loaded with wax, they produce 2 beats when sounded again. The frequency of A is 256. The frequency of B will be

• A. 250
• B. 252
• C. 260
• D. 262

Answer 1

Answer: (B)

252

Answer 2

n_A = Known frequency = 256 Hz, n_B = ?

x = 4 bps, which is decreasing after loading (i.e. x↓) also known tuning fork is loaded so n_A↓

Hence n_A↓ – n_B = x↓ ... (i) $\longrightarrow$ Correct

n_B – n_A↓ = x↓ ... (ii) $\longrightarrow$ Wrong

⇒ n_B = n_A – x = 256 – 4 = 252 Hz.