A tuning fork of known frequency `256 Hz` makes `5` beats per second with the vibrating string of a piano. The beat frequency decreases to `2` beats per second when the tension in the piano string is slightly increased. The frequency of the piano string before increasing the tension was

Options

A. 258 Hz
B. 254 Hz
C. 251 Hz
D. 261 Hz

Answer

C

Explanation

Two possiblities are there (i) 256 – n = 5 and (ii)n – 256 = 5 when tension increased, n will increase so 256 – n' = 2 is possible
`therefore 256-n=5impliesn=256-5=251Hz`