Question

The first loud sound is heard in a resonance tube when the air column is 26.2 cm and second load sound is heard when the air column is 80 cm. The diameter of the tube is

• A. 0.6 cm
• B. 1.2 cm
• C. 2.0 cm
• D. 1.6 cm

Answer 1

Answer: (C)

2.0 cm

$l_1+.3d=\frac{\lambda }{4}$...(i)

$l_2+.3d=\frac{3\lambda }{4}$....(ii)

$\lambda =2(l_2-l_1)=107.6cm$

substituting wavelength in equation (i)

$26.2+0.3d=\frac{107.6}{4}$

$d=2.3cm$