Question

A wave of frequency 100 Hz travels along a string towards its fixed end. When this wave travels back, after reflection, a node is formed at a distance of 10 cm from the fixed end. The speed of the wave (incident and reflected) is

• A. 20 m/s
• B. 40 m/s
• C. 5 m/s
• D. 10 m/s

Answer 1

Answer: (A)

20 m/s

Answer 2

Frequency $(\upsilon)=100 \,Hz$ and distance from fixed end = 10 cm = 0.1 m. When a stationary wave is produced, the fixed end behaves as a node. Thus wavelength $\lambda =2 \times 0.1=0.2\,m.$
Therefore velocity v $\upsilon \lambda =100\times 0.2=20 \,m/s$.