• # question_answer A wave of frequency $100Hz$ travels along a string towards its fixed ends. When this wave travels back after reflection, a node is formed at a distance of 10cm from the fixed end. The speed of the wave (incident and reflected) is: A)  $40\,m/s$              B)  $20\,m/s$C)  $10\,m/s$              D)  none of these

Here, frequency  $n=100Hz.$ Distance from fixed end $=10\,cm=0.1m$ When a stationary wave is produced, the fixed end behaves as a node. Thus, wavelength is given by             $\frac{\lambda }{2}=0.1$                 $\lambda =2\times 0.1=0.2m$ Hence, the velocity $V=n\lambda =100\times 0.2=20\,m/s.$