Question

In Quincke's tube a detector detects minimum intensity. Now one of the tube is displaced by 5 cm. During displacement detector detects maximum intersity 10 times, then finally a minimum intensity (when displacement is complete). The wavelength of sound is :

• A. 10/9 cm
• B. 1 cm
• C. 1/2 cm
• D. 5/9 cm

Answer 1

The correct option is B 1 cm

The bigger dots represent maximas and the smaller dots represent miniimas.

One of the tube is displaced by $5cm$.

Thus total path difference arises, $x=2\times 5cm=10cm$

Due to this path difference 10 maximas occur between the end points

(minimas).

$⟹\frac{\lambda }{2}+9\lambda +\frac{\lambda }{2}=10$

$⟹\lambda =1cm$