A string of length `0.4 m` and mass `10^(-2)kg` is tightly clamped at its ends. The tension in the string is `1.6 N`. Identical wave pulse are produced at one end at equal intervals of time, `Deltat`. The minimum value of `Deltat` which allows constructive interference of successive pulse is

Options

A. `0.05s`
B. `0.10s`
C. `0.20s`
D. `0.40s`

Answer

A

Explanation

`n=(1)/(2l)sqrt((T)/(m))=(1)/(2xx0.4)sqrt((1.6)/(10^(-2)//0.4))=10Hz. `
`:.` time period `t=1//n=(1)/(10)=0.1s.`
As distance between two fixed ends `=lambda//2`
`:.` for constructive interference, minimum value of time
`Deltat=(t)/(2)=(0.1)/(2)=0.05s`