Question

Distance between the 1st compression and the fifth subsequent rarefaction in a longitudinal wave if the wavelength of the wave is 20cm.

• A. 90 cm
• B. 80 cm
  
• C. 40 cm
  
• D. 45 cm
  

Answer 1

Answer: (A)

The distance between two successive compression or rarefaction is the wavelength $\left(\lambda \right)$. So the distance between compression and subsequent rarefaction will be $\lambda /2$

Thus, the 1st compression and 5 th rarefaction $=4\lambda +\lambda /2=\frac{9\lambda }{2}=4.5\left(20\right)=90cm$ as $(\lambda =20cm)$