Question

A student performed the experiment to measured the speed of sound in air using resonance air-column method. Two resonances in the air-column were obtained by lowering the water level. The resonance with the shoter air-column is the first resinance and that with the longer air-column is the second resonance. then,
A. (a) the intensity of the sound heard at the first resonance was more than that at the second resonance
B. (b) the prongs of the tuning fork were kept in a horizontal plane above the resonance tube
C. ( c ) the amplitude of vibration of the ends of the prongs is typically around `1cm`
D. (d) the length of the air-column at the first resonance was somewhat shorter than `1//4th` of the wavelength of the sound in air

Answer 1

Correct Answer - A::D
(a, d) At second resonance the length of air columnb is more as compared to first resonance. Now longer the length of air column, more is the absorption of energy and lesser is the intensity of sound heard.

As shown in the figure, the length of the air column at the first resonance is somewhat shorter than `(1)/(4)th` of the wavelength of the sound in air due to end correction.
`l + e = (lambda)/(4)` :. `l = (lambda)/(4) - e`