A string of length 20 cm and linear mass density `0.40 g cm^-1` is fixed at both ends and is kept under a tension of 16 N. A wave pulse is produced at t = 0 near an end as shown in figure, which travels towards the other end. (a) When will the string have the shape shown in the figure again ? (b) Sketch the shape of the string at a time half of that found in part (a).

Answer

A, B

Explanation

a. Velcity of the wave
`v=sqrt((T/m))`
`sqrt((16x1^5)/0.4)`
`=2000cm/sec`
`:. Time taken to reach to the other end
`=20/2000=0.01sec`
Time taken to see the pulse again in the origiN/Al position
`=0.01xx2=0.02sec`
b. At t=0.01s, then will be a trough at the right end as it is reflected.