A wave 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

Options

A. 5 `"ms"^(-1)`
B. 10 `"ms"^(-1)`
C. 20 `"ms"^(-1)`
D. 40 `"ms"^(-1)`

Answer

c

Explanation

As fised end is a node, Therefore distanece between
two consecutive nodes `=lambda/2=10` cm
`lambda = 20 cm = 0.2 m`
Now, `v=v lambda`
`therefore v = 100xx 0.2 = 20" ms"^(-1)`