I was asked this question in one of my tests:
"In an experiment to measure speed of sound by a resonating column a tuning fork of frequency 500 Hz is used. The length of air in the column is varied by changing the level of water in the resonance tube. Two successive resonance are heard at air columns of length 50.7 cm and 83.9 cm.
Is this statement true or false: The end correction in the experiment is 0.9cm"
The value of end correction I have calculated is coming as -0.9 cm. I understand that a positive end correction implies the wave is a little outside the tube but what does a negative end correction imply physically?