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

B

Explanation

For string mass per unit length is
`(10^(-2))/(0.4) = 2.5 xx 10^(-2) kg//m`
implies Wave Velocity `v = sqrt((T)/(m)) = sqrt((16)/(2.5 xx 10^(-2)))`
For constructive interference between successive pulses
`Deltat_(min) = (2l)/(v) = (2(0.4))/(8) ` = 0.1 s`