A tuning fork vibrates with frequency 256 Hz and gives one beat per second with the third normal mode of vibration of an open pipe. What is the length of the pipe? (speed of sound in air is 340 m s - 1 )

Step-by-step solution

Organ pipe will have frequency either 255 or 257   Hz . Using 255   Hz , 255 =   3 v 2 l , ⇒ l = 3 × 340 2 × 255   m ⇒ l = 200   cm . Using 257   Hz , 257 =   3 v 2 l ' ⇒ l ' = 3 × 340 2 × 257   m = 198   cm .