In an organ pipe ( may be closed or open of `99 cm` length standing wave is setup , whose equation is given by longitudinal displacement `xi = (0.1 mm) cos ( 2pi)/( 0.8) ( y + 1 cm) cos 2 pi (400) t`
where `y` is measured from the top of the tube in metres and `t` in second. Here `1 cm` is th end correction.

The air column is vibrating in

Options

A. First overtone
B. fifth harmonic
C. third harmonic
D. Fundamental mode

Explanation

`(2pi)/0.8 =(2pi)/lambda` So `lambda=0.8` and effective length of air column = 0.99+0.01 = 1m
So `l/lambda=5/4 rArr l=5 lambda/4`, so five half loops will be formed
`l=5(lambda/4)` so second overtone