Read the following paragraph and answer the following questions :
In a reaonance tube apparatus a tunning fork of unknown frequency after striking with a rubber pad is held near the open end of resonance tube. The airm column of resonance tube can be varied. For definite length of air column is resonance tube. the airm column of resonance tube can be varied. For definite length of air column in resonance tube, standing waves are set up due to superposition of sound arives travelling in oppositc directions. the smallest value of length of air column which intensity of sound is maximum is 10 cm. Take speed of sound 344 m/s.
The frequency of tunning fork used in the above experiment is :

Options

A. 533 Hz
B. 860 Hz
C. 960 Hz
D. 1090 Hz.

Answer

B

Explanation

`(lambda)/(4) = l rArr lambda 4 xx 10 = 40 cm = 4 m `
`v = (V)/(lambda) = (344)/(0.4) = 860` Hz.
so correct choice is b .